When Dr. Elaine Abrams founded the Family Care Center at Harlem Hospital Center, one of New York's first clinics for the treatment of children with H.I.V. and AIDS, that ''treatment'' consisted mostly of easing their deaths. Through the early 90's, 10 to 20 babies were dying at F.C.C. every year; at one point, an H.I.V.-infected patient lived to the age of 6, and the doctors considered that child a medical miracle. Today -- thanks to protease inhibitors, combination therapy and other improvements in the treatment of the virus -- the average age of the approximately 135 H.I.V.-infected children being treated at F.C.C. is 13 and rising. It's possible to imagine the day when the clinic itself will be obsolete. ''Over the years,'' Abrams says, ''we've turned from a medical program with mental-health support to a mental-health program with medical support. It's the last leg of the journey.'' But that last leg has involved psychological complexities no one could have foreseen. Children born with the virus also aren't born with the knowledge that they carry it; this was a nonissue when few survived infancy, but as their prognosis improved, the whole issue of disclosure -- of what they know about their own disease, and who tells them, and when, and how -- began to reveal its intricacies. ''I used to believe that all the kids knew,'' Abrams says. She tells of one 14-year-old who knew all about T-cell counts and taking meds but had never contemplated being H.I.V.-positive. ''The kid had been taking these drugs every day for three years without knowing,'' Abrams says. The fact is, they often don't know, and it isn't a simple thing to tell them. Over the last decade, the revolution in medical treatment of H.I.V. has created a generation of young people whose unexpected maturation is both a miracle and an extraordinary challenge. According to Claude Mellins, co-founder and co-director of the Special Needs Clinic at New York-Presbyterian/Columbia hospital in New York, about 70 percent of her young patients with H.I.V. do know their status by the time they're 10 or 11. Still, from the outside, the idea that any H.I.V.-infected child -- that other 30 percent -- could reach adolescence without knowing he or she has the disease threatens to beggar belief. For starters, the children have usually spent most of their lives taking several different drugs several times a day, drugs notorious for their foul taste and vicious gastrointestinal side effects. Many of them have spent time in the hospital, a setting in which the likelihood of their overhearing a diagnosis of their own disease by accident is high. How can they not know? How can their parents justify not telling them? And what happens when a child finds out?

The walls of A.'s living room are covered with framed photographs of her six children and stepchildren -- most of them school portraits in the familiar three-quarter pose, forming a kind of time-lapse of their youth -- and to look at them, you would never know which child was the chronically ill one. But then to look at A., an attractive young mother, soft-spoken and articulate, you wouldn't know that she has been, like the second of her four boys, H.I.V.-positive for more than a decade. It is so easy, in fact, to conceal her son's H.I.V. status that she has successfully kept it a secret from nearly everyone: her friends and neighbors, her other children and even, amazing as it seems, from the boy himself. Infected in the womb, he has taken medication nearly every day of his life and has never really been told why. She points out his picture on the paneled wall. He is 11.

''I have not yet discussed it with him,'' she says. ''He's sweet, but he's still a little immature, and I don't think he's ready to handle it. His siblings either. I don't think that they would understand right now. I'm planning on trying to disclose to him at the beginning of next school year. He's very popular in school. It'll be hard for him if people find out. Not only do I have to be careful of maybe he might blame me for his illness, but people might treat him bad because he has it.'' A. lives with her husband and children in a dark, toy-strewn, spacious apartment in the South Bronx. Her own health is very good, though she was asleep when I arrived -- the aftermath of one of the migraine headaches that have begun plaguing her lately, whether from her medication or from some other, perhaps stress-related cause, she isn't sure. ''We've done very well for the last 11 years hiding it,'' she told me. The ''we'' refers to her husband, who is H.I.V.-positive as well. ''It's difficult, because I'm running back and forth to the hospital. I'm always in an appointment; my husband is in an appointment. We tell the other kids when my son is taking his meds to leave the room, because they ask questions. Why does he have to take medicine? Why does he always get sick? Why does he see Dr. Champion and I don't?'' Susan Champion is a pediatrician at the Family Care Center, which provides complete medical and mental-health treatment for children with H.I.V. and their families. They do everything for these children except the one thing that by law they are barred from doing without the parents' explicit consent, and that is to disclose to children the reason they are at the Family Care Center in the first place. When A.'s son asks questions -- which he does -- she tells him he has a blood disease, which, as she points out, is not untrue. ''I'm terrified of people knowing,'' she says, ''very terrified even for myself. No one knows. My brother is the only one in my family that knows. Not my dad, not my sisters, my stepmom, no one.'' What is she most worried about? ''The simple things, you know. If it's not the sympathy, it's the pushing away. It's either one or the other. You either get the sympathy, or you get the boot. No one wants to be bothered. No one wants to touch you -- don't come over here, don't get nowhere near her, you know. And that's what I'm afraid of for my boy with the other kids, because kids are cruel. And there are a lot of parents that are cruel too.'' There are two issues here, of course: 1) what's best for the long-term physical and mental health of A.'s son as he grows older and inevitably more aware that an enormous secret has been kept from him; and 2) the prospect of a happy, charismatic, handsome young boy approaching the age of sexual activity who has H.I.V. and doesn't know it. And then there is a separate and, within some families, greater concern: that the child, once in possession of the family secret, will not prove adept at keeping it from those outside the family. One study found that 45 percent of children, upon being told they had H.I.V., were also told that they were not allowed to share that information with anyone else, period. Charging them with the responsibility of keeping such a secret ratchets up the stress level for everyone involved. ''To tell you the truth, I'm not ready,'' A. says. ''I think it's more me than him. Maybe he can understand. You know, the doctors are like, 'O.K., are you talking to him about it?' Once in a while we discuss things. I'm not so much scared that he'll blame me, because if he does, it is my fault, because I should have been tested. It was only because I had unprotected sex. It's not like I was shooting up drugs and things like that. But at the time, we weren't very educated about what could happen. I'm afraid that he won't feel like he's the same as everybody else. He thinks he's a little teenager. He's into the music, the TV, into girls and wrestling. And I think if I tell him, he won't feel the same. I think he'll be a different person. And I don't want him to change. I want him to always be himself.''

At the end of our conversation, footsteps came crashing down the hallway, and her son walked into the living room. We were introduced, and he nodded shyly. He is poised between impish and handsome. It was not so very long ago that to meet such an 11-year-old boy would have been unimaginable.  

By 1990, as many as 2,000 children nationwide were being born perinatally infected -- that is, infected in the womb -- with H.I.V. Few were expected to live more than two or three years. (Recent news reports have raised the possibility that in the 1980's and into the early 90's, AIDS drugs were tested on foster children in New York City, and elsewhere, without adequate precautions.) By 1994, a major study was under way to determine whether the relatively new AIDS drug AZT, if administered to H.I.V.-positive pregnant mothers, would influence in any way the transmission rate of the virus to their unborn children; the results were so immediate and decisive that the tests were unblinded, and AZT therapy was made generally available. With the new treatment, the so-called vertical transmission rate was reduced from roughly 25 percent to 8 percent. Since then, a host of factors -- including the adoption of recommendations against breast-feeding -- have combined to all but eliminate vertical H.I.V. transmission. Women who have been H.I.V.-positive for a decade or more can, with early and consistent drug treatment, bear children with very little risk of transmitting the disease. The transmission rate is now 1 percent to 2 percent, which translates to about 200 H.I.V.-infected infants born each year nationwide. In New York City in 2003, the total number of perinatal H.I.V. transmissions was five. Harlem Hospital has had just two in the last four years. And the advances in the medical treatment of H.I.V. wrought a similar change in the lives of the perinatally infected themselves. By 1999, the life span for children infected in the womb ranged from 8.6 to 13 years; today that life span -- provided the children stay on their drug regimens -- is open-ended, and their illness has turned strikingly from terminal to chronic. Though this can be viewed only as a blessing, it is simultaneously true that these children tended to be raised with little thought of preparing them for an independent adulthood that seemed not just unlikely but also out of the question. ''I spoiled her rotten, because I thought she was going to die,'' one adoptive mother told me. ''How could you not?'' A significant part of ''spoiling'' them, in most cases, was withholding the information that they had H.I.V. at all. Now, as these children grow older and savvier, a small culture of medical professionals -- men and (mostly) women who have been on the front lines of this initially hopeless battle from the beginning -- struggle to influence what their patients are told about their conditions, and when, and by whom, without further damaging a family framework that's often extremely fragile to begin with. Their success rate is astonishingly high. At one end of the spectrum are young adults who have developed a precocious sense of self-reliance and a fearlessness in the face of others' prejudices; at the other end is a case like A.'s son -- a child at the cusp of sexual activity, ignorant of carrying an infectious and potentially lethal disease, surrounded by adults who either can't make themselves tell him or are forbidden to do so by law.  

K  is a 20-year-old Bronx woman who has been positive since birth but didn't find out until she was 13 -- very shortly, by her own account, before she became sexually active. In her case, it wasn't simply a question of her mother's not being able to bring herself to tell her: her mother, having learned of her own positive status three years earlier, couldn't bring herself to have K. tested at all, so great was her fear of what the test result would be. K. learned the truth when visiting a doctor to try to discover why she had stopped growing. (In the early years of the epidemic, H.I.V.-positive children were often marked by significantly retarded physical development; with improved medication, that's much less the case.) ''It was one big snowball for me,'' she says. ''I found out I'd stopped growing, I found out I was positive, that my mother was positive, that my father gave it to my mother, all at the same time. It was like, my first week in high school. As soon as they told us, this stream of tears just came. But it wasn't like a big sob story. It just happened. We got over it, and then we went shopping. I guess as the years go on, I still process it, but at that moment it was like, if I ignore it, then it's not gonna bother me.''

This is an attitude, as she recognizes, that she picked up from her mother. ''She's a very secretive person,'' K. says, shrugging. ''She doesn't tell us things. My grandmother too. She runs a whole AIDS section of her church, but she won't tell people that I'm positive, or that her daughter's positive, or that her son'' -- K.'s uncle -- ''is positive. I think secretly she's kind of ashamed. She wants to appear as this good Samaritan, where she's helping out strangers, whereas she's really doing it because someone in her own life is affected by it. She doesn't want that dirty little secret, I guess, in her life.'' Some families decide that that burden of secrecy is so great, and so unjust, that the best response is to disclose to everyone, to turn their plight into a means of educating their own community or society at large. Many parents also expect, not unreasonably, that such proactive honesty will make their children feel better about themselves. But studies show that such broadly public disclosure -- appearing on TV, going on speaking tours -- actually turns out, in terms of the children's self-esteem, to be a mixed bag. Not to mention that the community at large sometimes resists being educated. Most everyone old enough to remember the worst days of the AIDS crisis remembers Act Up, the confrontational activist group instrumental in raising AIDS awareness throughout the 80's and 90's; less well remembered is that there was an offshoot of Act Up devoted to the cause of H.I.V.-positive children, called the Just Kids Foundation. E., for example, was eager to do something to help in the fight against the epidemic; she decided to become a foster parent to a child with the disease, knowing full well that that child's life would probably be a short and difficult one. In fact, doctors gave the infant girl she took responsibility for and later adopted, who was born not only H.I.V.-infected but also addicted to crack cocaine, two to three years to live. E. is enough of an old-time lefty herself to quote Eldridge Cleaver in conversation, but when she went to those Just Kids meetings, she sometimes found she didn't agree with what she heard. (The initials throughout this article are derived from people's actual names. In this case, the initial is not; it was chosen to further protect E.'s daughter's privacy.) ''It was very similar, very radical,'' she says. ''Heavy pressure to disclose to the children at a very early age, to start certain medications at a very early age.'' But broader disclosure was frowned on. ''It was 'don't ask, don't tell.' If the teachers at the child's school don't know enough to wear rubber gloves if a kid bleeds, then that's too bad for them. But I didn't feel that was fair to the teacher. I felt it was my responsibility, and if there were consequences, then I would take those consequences.'' The radical approach to disclosure -- that the child must know everything, because there is nothing to be ashamed of, and that no one else has the right to know anything, because it's none of their business -- was a defensible one, but also one containing a seeming contradiction whose subtleties were bound to be lost on the children themselves. E.'s daughter's own experience wound up bearing out that very contradiction. When she started asking questions, around age 8, E. (who had by then adopted her) told her the truth with the help of a children's book written specifically for children with H.I.V. As children's books tend to do, it represented a difficult experience in an honest but also optimistic light, its primary goal being to strengthen the reader's self-esteem. It went well. It went so well, in fact, that when the girl returned to school, she decided to tell her news to her friends. ''Her teacher was beside herself,'' E. says. '''What are the parents going to do?' And this was a very progressive school. There were all these conferences. They hushed it over. They told the girl to keep it to herself.'' To make matters worse, one parent who expressed alarm about this one-girl disclosure campaign was, according to E., one of the girl's own doctors. Some kids, like E.'s daughter, enter the foster-care system virtually from the moment they're born; for others, foster care is a later stage in a childhood marked by progressive loss. V., who works in a Manhattan bakery, lost his mother to AIDS when he was 7, and in the years when they were together, they were both sick all the time. ''The hospital was like my second home,'' he says -- in many ways a more stable home than his primary one. ''All the nurses knew me. They took care of me like I was their son. It wasn't scary at all. Now it's scary, because I know what the situation is. If I'm in there now, I want to try to get out as fast as possible.'' V. went into the foster-care system after his mother's death. Eventually he found a stable home, and when he was 13 that family adopted him. ''It was O.K.,'' he says. ''I mean, it was family, but it can never happen like family family. I will never know what family is.'' As he grew older and more independent, things became more argumentative at home, until it reached the point where he moved out and went voluntarily into a group home for H.I.V.-positive teenagers; at 18 he moved into his own apartment in Washington Heights. ''I grew up faster than I was supposed to,'' he says. ''Everybody, they look at me, they're like, No way you're 20.'' He dreams of opening his own bakery, maybe in New York or Miami. He dates, but right now he is disconcerted to be facing the end of the most solid, long-term relationship in his life, and that's with his pediatrician. ''I've know him since I was 18 months,'' he says, ''longer than I've known myself.'' As for many in his generation, the necessary transition to an adult doctor is psychologically fraught; patients like V. haven't had many stable adults in their lives, and so it's not so easy to give one up. ''I don't trust a lot of people,'' he says. ''That's the problem I have now. Like, I could trust you. But I don't trust you. You know what I mean?'' It's a transition a lot of H.I.V.-positive young people find traumatic. Their doctors are quite often the most long-term, if not the only, responsible and reliable adults in their lives. ''There's this one patient of mine, a young woman,'' says Dr. Stephen Arpadi, who started one of New York's first family AIDS clinics at St. Luke's-Roosevelt Hospital. ''Her parents both died by the time she was 10. Her older brother was really incapable of taking care of her. She had her own adolescent issues about taking medication, and she became quite sick and at some point lost her ability to walk. Now she's on the other side of adolescence, and she's actually a fairly hopeful character right now. But whenever I'm with her, she never fails to say to whomever we come across: 'That's Dr. Arpadi. He knew my mother. He knew my father.'''  

It's the families most in need of the mental-health services that a place like F.C.C. provides that prove the most difficult to engage. It can take months, or years, and sometimes it doesn't work out. ''This is not like cancer,'' says Sheila Ryan, program director of the Special Needs Clinic at Columbia-Presbyterian. ''These families are not a cross-section of the population. These issues would be agonizing for any family to deal with, but the families that are likely to be dealing with H.I.V. are more likely to have problems with substance abuse and mental illness. These are poor families, and even within the poor community more likely to be fragile than others on the same block.''

It was partly in an effort to shore up the fragility of these families that a movement to safeguard their privacy grew up in the wake of the AZT trials in the mid-90's. With such a remarkably effective treatment newly available, the issue became whether H.I.V. testing for pregnant mothers should be mandatory, for the sake of the health of their children. But this was at the height of the epidemic and the panic it engendered; the specter of discrimination against the mothers themselves -- including the possibility of their being judged unfit on the basis of those tests and having their children pre-emptively taken away from them -- kept this initiative from becoming law. H.I.V.-confidentiality statutes are state-specific; today in New York, testing newborns for H.I.V. is mandatory, but testing their mothers is not. Such sweeping policies, whether they come from a group like Act Up or from the government it opposes, will always have unintended consequences. Q., a 47-year-old woman who lives in the Bronx -- active, physically fit, a self-professed vitamin devotee -- is the mother of five children. The fourth, a daughter, was born at Harlem Hospital Center in 1993, and unlike her siblings, she was sick from Day 1. She had recurring yeast and sinus infections and difficulty walking and crawling, and though she could clearly hear and understand others, she never tried to speak. Q. hadn't returned to Harlem Hospital Center since the birth, going instead to a variety of hospitals and clinics closer to her home, where doctors dispensed antibiotics to treat the infections, which partly cleared up for a day or two and then came right back. She was sure there was something wrong with her daughter's immune system. She even asked one doctor to test her daughter for H.I.V., and he wouldn't, saying that the test was too painful to perform on a clearly healthy child and accusing Q. of something he called parent paranoia. Two months later, Q. took a vacation to visit an old friend in North Carolina. Q.'s daughter was sick again. Q. took her to Duke University Medical Center, without an appointment, and after sitting there for a while, she rev.finally stopped a doctor in the hallway. ''I said, 'I think she's H.I.V.-positive,''' Q. remembers. ''The doctor said, 'What do you want me to do?' I said, 'I want you to test her for everything.' That was on a Monday. She said, 'Come back in on Thursday and we'll give you the answer.''' The answer was that the girl was indeed H.I.V.-positive. Q., having rev.finally found a doctor capable of listening to her, now had to explain that she was only there on vacation. Could the doctor recommend a good facility for the treatment of pediatric H.I.V. back in New York? ''Do you know,'' the doctor asked her, ''where Harlem Hospital is?'' Thus, Q. returned to the hospital where her daughter was born. Dr. Abrams and her colleagues immediately started aggressive drug therapy for the child, who not only didn't die but thrived: now 12, she's an honors student who also excels at tae kwon do and basketball. The push for openness with children about their own condition is far more likely to come from the doctors themselves and toward parents or caregivers whose reluctance or fear or denial grows more entrenched with the years. The doctors' experience has tended to bear out what common sense might suggest -- that the outlook for the child's emotional well-being in the wake of disclosure is greatly improved if the bad news has come from his or her own family members, rather than despite them. ''Trust is most important,'' says Dr. Lori Wiener, coordinator of the Pediatric H.I.V. Psychosocial Support and Research Program at the National Institutes of Health in Bethesda, Md. ''It's very hard to swim back up that river. You don't want them to be saying to you, 'What else have you lied to me about?''' At the same time, the doctors worry that putting too much pressure on the parents to disclose might lead them, in an effort to escape that pressure, to stop bringing the children in for regular treatment at all. ''The typical response is, 'He hasn't asked, so I haven't told him,''' Abrams says. ''But ultimately most families do what's best for their child. Just not necessarily on my time line.'' Part of the tendency toward silence has its roots in the bitter experience of the families themselves. As one early research study dryly phrased it: ''The overwhelming majority of pediatric H.I.V. cases occurs in urban minority families that have experienced poverty, early or violent family deaths, racial discrimination, lack of basic services, drug addiction and unstable family configurations. Strategies for coping with the pervasive losses these families have encountered on all fronts generally do not include full and open discussion.'' But in the end, most of the reasons that parents have such a hard time delivering such monumentally bad news to their own children transcend any social or economic circumstances. Parents often experience their reluctance to tell the truth as protective. There's the constant fear that it's too soon, too early, that the child is not ready to make sense of it, as if there were any sense to be made of such news. ''They'll say, 'Look at her,''' Wiener says. '''She's out there playing. She's happy. Why would I want to burden her with this information that will change her life forever?' Or, 'She's too young to understand anyway, so what difference will it make except to add something that's really stressful for her?''' Many parents also fear that the news itself will make the child's condition worse by adversely affecting his or her will to live. It's worth noting that while the disease itself may be relatively new, this sort of secrecy -- even on the professional level -- is not: as recently as the 1960's, it was not unusual for cancer patients to die without the word ''cancer'' once being uttered in their hearing, not even by their doctors. Avoiding the subject was presumed to be merciful, whereas honesty was simply hope-killing. The subject is even more charged when the H.I.V.-positive child lives with a biological parent. Such parents have good reason to fear, at least initially, anger and rejection from their own children; they may also dread the prospect that the conversation will have to include a disclosure of their own H.I.V. status, as well as the behavior that led to it. ''It's a web,'' Wiener says. ''You can't just go to the child and say, O.K., this is what you have. It means disclosing other family events.'' Sometimes the child himself will force the issue, even if unknowingly. Dr. Warren Ng, chief psychiatrist and co-director at Columbia-Presbyterian's Special Needs Clinic, remembers a patient whose ignorance of his own condition suddenly became an issue when he started talking about his desire to have sex on his 15th birthday, which was quickly approaching. In that case, the clinic not only called in the boy's parents but also put them through family counseling in order to find for them, Ng says, ''a script they were comfortable with.'' But the greatest inhibitor -- which the child's good health and outwardly normal childhood only aggravates -- is guilt. When Q. faced her own diagnosis shortly after learning her baby daughter's, her eldest child was 16, old enough to handle the information in a mature way; still, Q. couldn't bring herself to tell that daughter for two more years. ''They knew their sister took meds,'' she says of her other children. ''And they knew I took meds. They just didn't know why. They knew it was important. They'd say, 'Mom, did you remember to take your meds?' But they didn't know what it was for.'' The doctors at the Family Care Center urged her to start discussing it directly with her family. ''But I'm not a person who's easily swayed,'' Q. says. ''It wasn't that I wasn't ready to discuss it with my child but that I wasn't ready to deal with the fact that she might feel ashamed of me over it, or angry with me. I wasn't willing to hear her say: 'Ma, how could you have done that? What kind of life was you living?'''  

Sometimes the disclosure conversation itself, when it rev.finally occurs, can become another variant of denial: parents rush through it in the vain hope that having talked about it once, it will thus be dismissed, and they won't need to talk about it anymore. What they learn instead is that children don't process information -- especially difficult information -- in the same way adults do. The mantra of the doctors and social workers is that disclosure is not an event but a process; usually the conversation needs to take place several times before its reality sets in for good. Mellins tells the admittedly extreme story of a graduate assistant in a research study who went in to interview a child in the Family Care Center for a study on some element of the psychological fallout of his ailment. She began by asking him what he could recall about his reaction to the news that he had H.I.V. The boy stared at her. ''I have H.I.V.?'' he said. In fact, this child had been told of the diagnosis not just once but several times; the doctors called in the people who were caring for him and went over everything again. How do children react to the news when it sinks in? Surprisingly, perhaps, they tend not to ask about death right away. ''The issues about death come out in other ways,'' Mellins says. ''They try to make certain things happen quickly, like wanting to have a baby or get married. At age 14 or 15, they want these things to happen. And if you press, you start to learn that it's because they're afraid they won't have a regular life span.'' ''The two issues they keep coming back to,'' Sheila Ryan of Columbia-Presbyterian says, ''are the permanence of the virus -- the idea that there's nothing you can do to get rid of it -- and what kind of impact it will have on their capacity to have children, which is partly a question about the ways in which they might be impaired or maimed or less than others.'' ''Sometimes kids find ways of protecting themselves from the information,'' Ryan adds. ''One girl who was in here, at the time we rev.finally said the word H.I.V., she said, 'But I know I don't have AIDS.' I said, 'How'd you figure that out?' And she said, 'Because if you have AIDS, you're skinny and living in Africa, so I know I don't have it.' Or another girl who was 15 -- her mother told her the week before she came in here for the first time, and her response to that was simply that her mother had lied to her.'' In the end, it was Q.'s daughter who forced the conversation with her mother. Like some who live with H.I.V., she takes the medicine via a surgically implanted feeding tube; after asking for years, and being put off with answers like, ''Because I'm your mother and I say so,'' she demanded to know why she had to take all this medicine daily that no one else she knew in her family, apart from her mother, ever had to take. They had the conversation, and now the child herself is part of the stressful balancing act -- on the one hand, H.I.V. is nothing to be ashamed of; on the other hand, don't go telling your friends about it because it's none of their business. Does Q. worry that as her daughter gets older and more independent, she'll start making those decisions -- whom to tell about the family secret, whom not to tell -- on her own? ''Right now, it's nothing she would share,'' she says. ''She's at the age when children don't want to be different from their friends. She would not want to stand out. She would not say anything about H.I.V., or the people who have it, that would make her friends turn around and say, 'How would you know?'''  

There was no one moment when all of these parents, who once thought their time with their children would be so limited, were told that the old prognoses had been thrown out the window; the necessary emotional adjustments had to be made gradually, not to mention improvisationally. P. is a former New York City employee who went on permanent disability after developing a work-related lung ailment. She became a foster parent -- ''I didn't even know you got paid for doing it,'' she says. ''I just thought that if it was something you could manage to do, you did it'' -- and over the last 15 years, some 60 children have lived in the Bronx apartment she shares with her sister. (In fact, foster parents of H.I.V.-positive children under the age of 5 may be paid triple the usual rate.) Some stay for a short time, some for a long time, and she has legally adopted two of them, including a boy, now 12 and positive since birth. He went into the foster-care system in 1994 when his aunt, with whom he was living, learned that the boy's mother had H.I.V. and announced that she no longer wanted the 16-month-old baby in her house.

The aunt never even had him tested. That fell to P., and when the results came back positive, the doctors at Harlem Hospital told her that the boy might not live to the age of 4. ''I used to ask him,'' P. remembers, '''Did you have a good day today?' Every day had to be a good day. Because I was really afraid he might not make it.'' She still remembers the party they gave when, against expectations, he turned 4 after all. He turned 5, and 6, and then one day -- still unaware of his own condition, though he would complain about the AZT he had to take as often as every 12 hours -- he had a surprising request. ''He asked for a brother,'' P. says. ''He said, 'I need someone to play with.''' She thought over his request, and then she went to the foster-care agency with an unusual request of her own. She wanted to adopt another child, with three conditions: it had to be a boy, he had to be younger and he had to be H.I.V.-positive.

''They really thought I was crazy,'' she says. ''But if, God forbid, anything ever happened to my older boy, I didn't want him to be able to look at me and say: 'You knew all along. That's why you let me have this brother, so that you could have a healthy child, so you could replace me with a normal person.''' His little brother is now 6 and has not yet been told he's positive. His older brother helps encourage him to stay on his medicine. It's four years now since he learned of his own H.I.V. status. He had his suspicions, in part because of the children's books about H.I.V. and AIDS that P. made sure were on the bookshelf in his bedroom. rev.finally the doctors convinced her that her son needed to hear, as she says, ''the letters that go with the problem.'' She tells the story of how she then took him to a restaurant for lunch, just before one of his scheduled appointments at the hospital. She let him pick out whatever he wanted; when the waitress came and took their order, she said, ''There's something I'd like to talk to you about.'' ''It can wait,'' he said. The appetizers came, and then the main courses, and she said she really needed to talk to him. ''I know you do,'' he said. ''Don't ruin the food.'' They finished their lunch, paid the check and walked all the way to the hospital before she could make herself go through with it. ''Come here,'' she said. ''Don't,'' he replied. But she did. And when it was over, she was in tears, and he seemed fairly calm. ''Is that all it is?'' he said. ''I thought you were going to tell me I had asthma, like you.'' Seeing her struggle for breath, that was what scared him. He sometimes asks about his biological mother; P. is legally forbidden to give him any information that might help him contact her until he turns 18. But the fact is, not only does she know the identity of her son's biological mother; she saw her once in a while. She seemed healthy and has other children. One Sunday, P. recalls, she and her son met one of these children. They ran into his aunt -- the same one who put him into foster care as a baby because she suspected he might be ill -- with another of her nephews, his half-brother. To P.'s son, both of these people were strangers. ''Is that who I think it is?'' the aunt said pleasantly. ''Well, of course it is,'' P. said -- and, not knowing what else to do, she introduced the children to each other. Her son, who lives in a home where a premium is placed on etiquette, said, ''Pleased to meet you'' to the other child and put out his hand. ''Don't touch him,'' the boys' aunt said.  

Those on the leading edge of this unexpected generation are just now moving into the adult phase of their suddenly open-ended lives; after childhoods marked by secrecy and fatalism and prejudice and loss, it seems too much to expect that they should figure out how to become responsible adults. But it happens every day. Ben Banks, a 26-year-old who lives in Virginia, had a rare form of cancer in infancy; on the day of the physical exam that was supposed to mark his 10-year freedom from that cancer, when he was 12, it was discovered that he had contracted H.I.V. from a blood transfusion. (The blood supply began to be screened in 1985.) He came home from school, walked up the stairs and found his mother sitting on the bed sobbing, having just hung up the phone. ''That was the doctor,'' she said. ''You're H.I.V.-positive.'' No elaborately planned, properly tempered disclosure conversation for him. Still, this was in 1991- six months before Magic Johnson's public disclosure of his diagnosis -- and he had to be careful, much more careful than those who would follow in his footsteps, about what he said and to whom. His school gave him special permission not to go to the nurse -- to take his own medication in private, in the bathroom before lunch -- because of the panic they feared would ensue if anyone recognized the name of the drug he was taking. On one particularly harrowing day, he sat in health class and watched the TV movie ''The Ryan White Story'' while his classmates joked cruelly all around him.

But Banks, having already survived cancer, was a remarkably resourceful teenager. He told his best friend, and then a few other friends, and then a group of his classmates at James Madison University, and he now serves as a spokesman for the Elizabeth Glaser Pediatric AIDS Foundation. In 2003, he married. As for the turning point in his own understanding of his disease -- from death sentence to manageable illness -- it may have come when he was 17 and applied to the Make-a-Wish Foundation, which grants the wishes of extremely ill children. His application was disqualified. Stung, he called up his doctor. ''Ben,'' the doctor said, ''why don't you give that wish to a child who really needs it. You're not going anywhere.''  

Their continued good health, indeed their survival, depends on their continued adherence to the same strict drug regimen that has kept them alive thus far. Keep taking your medicine: another simple idea that in the lives of these young people turns out to be burdened with psychological complexities -- this despite the fact that even a few missed doses can allow the virus to develop a resistance to a given drug, permanently compromising or nullifying that course of treatment. What, apart from the desire for a respite from the sometimes grievous side effects, would induce someone to stop taking lifesaving medication? Primarily stress and depression -- circumstances to which any teenager might be considered at risk, but to which an adolescent concealing a stigmatizing condition is especially prone. ''There is definitely a relationship between adherence and depression,'' Wiener says. ''There's a tremendous amount of stress associated with lying, with living a life of secrecy.'' Going off meds can also be an adolescent's expression of the desire to hold the reins of his or her own life for a change, even unto self-destruction, broadly analogous to an anorexic's refusal to eat.

But others simply overlook their own welfare, often because even as children, their first responsibility was the welfare of others. Siomara Cruz is an effervescent 21-year-old, the fourth of six children; she and her two younger siblings were born with H.I.V. Those siblings each died at the age of 5; the eldest child in the family, eight years Cruz's senior, was so unstrung by the deaths that he left home. Their mother passed away when Cruz was 11. She and her older sister moved in with their grandmother, but that didn't last long; she has been looking after herself since she was 16. Now she works at an office-supply store in Manhattan; some of her co-workers know her status and some don't. ''When you hear people just talking and joking around, you can get a sense of the type of person they are,'' she says, ''and I don't think a lot of them can handle it, honestly. I don't want to have to do a 'Philadelphia' on them.'' In the summers she serves as a counselor at the Joey Dipaolo AIDS Foundation's camp in upstate New York for kids with H.I.V. Counselors frequently have a hard time getting campers -- who are enjoying a rare interlude from anxiety about their disease -- to take their meds; one way they do it is by bargaining with them, saying: ''Look, if you take all your pills, then I'll take one of the purple ones with you. We'll do it at the same time.'' This, even if the ''purple one'' is not a medication prescribed for them; indeed, some counselors aren't H.I.V.-positive at all. Then they stay up all night thrashing and moaning and admitting that they had no idea how justified all the reluctance to take the medication really is. Cruz laughs affectionately as she recounts this story. Then I ask her if she suffers any such side effects from the medication she's taking. ''The ones I'm supposed to be taking?'' she says, laughing. ''Yeah.'' She doesn't take them? ''I just can't deal with them. They make me feel worse. I just don't want to live my life like that. If I didn't have to take medicine, if I could drink something that would help me or take like a Flintstones vitamin, I would. I spoke to my doctor. She's like, 'Siomara, we have to talk.' It's like seven pills I'm supposed to take. If I take them in the morning, then when I get to work I'm just ready to hit the floor. But then I try at night, and I can't sleep because I'm so sick. I live with my boyfriend, and when I'm sick like that, there's nothing he can do. He feels so helpless. I can't put him through that.''  

However understandable the desire to deny, if only for a little while, the burden of their illness, neglecting to take meds consistently is about the most unwise thing H.I.V.-positive young people can do. There's the risk of undermining their own course of treatment. And as if that weren't enough, they could develop (and potentially could transmit) a strain of the virus that has built up all sorts of resistances to existing medication. As Mellins says, ''How do you instill within kids a healthy sense of sexuality and at the same time a sense of fear?'' Thus, the doctors say, the next frontier in the lives of this generation is ''peer disclosure'' -- the tricky process of telling friends and especially potential sexual partners about their status. The mercurial quality of romance in your teens and 20's makes the disclosure question especially risky: the boy you think you'll be with forever may be a distant memory in a month or two, but if you tell him in an intimate moment that you're H.I.V.-positive, the stakes of normal adolescent gossip will be exponentially raised. K. says that she would never date anybody in school or anybody who lives in her neighborhood. In high school she had a boyfriend who found out her status by accident, through something he found in her backpack, and she has resolved not to let that kind of thing happen again, for everybody's sake. ''Now I just think of it as the first thing that needs to be done, before the first physical thing happens,'' she says. ''I just have to get up the nerve to do it. It's like you have to find the right moment, feel the person out. Usually I go down the line of different diseases -- what would you do if you had this disease, that disease, what would you do if your arm was chopped off? I kind of try to play with it -- would you still be with me if I had no left pinkie or something?''

The prejudices for which she feels them out are by far the most significant obstacle between those in her position and a ''normal'' love life -- up to and including starting families of their own. The same safe-sex practices that are drummed into the heads of every teenager and young adult these days are sufficient to keep them and their partners safe as well. And today's low vertical transmission rate means that -- with the same AZT therapy, recommendations against breast-feeding, etc. -- their own chances of having uninfected children are excellent. The perinatally-infected patients in Abrams's and Mellins's clinics tend, Mellins says, to be pretty savvy about such cutting-edge insemination techniques as ''sperm spinning'' designed to help them conceive without endangering the health of their partners. It should be said, of course, that the conditions that allow such a relatively sunny image of pediatric H.I.V. as a manageable disease -- one whose transmission from mother to child it is possible to stop -- belong exclusively, at the present time, to the developed world. Recommendations against breast-feeding, for instance: not so simple in impoverished places or where access to clean water can't be taken for granted. Abrams says that until recently children ''have not really been included in the international dialogue around H.I.V. care and treatment. In terms of the number of individuals treated in Africa, they've been neglected.'' And so, even as the Family Care Center she founded at Harlem Hospital Center moves blessedly in the direction of obsolescence, she has spent the past two years with a team helping to establish family-care pilot programs on the F.C.C. model in South Africa and elsewhere. ''So they don't have to start from scratch,'' she says.  

But here in the United States, K., like her peers, has come to terms with the idea that what once amounted to a death sentence has been lifted. The air of provisionality that hung over her childhood is not easily dismissed, but she has turned it into a kind of motivation. ''A lot of my friends my age that don't have H.I.V. are like losers,'' she says. ''They sit on their rear all day and do nothing. I have a job, I go to school, I do everything I need to do, and I think it's because I want to make sure I do it before I pass. It's my goal to just get it all done. She works full time while going to college in the hope of becoming an architect. No one who meets her would doubt that she has the resources to achieve such a goal; for others, though, with different goals, their H.I.V. status -- no matter how easily controlled or concealed -- isn't so easily denied. ''I have two patients,'' Ng, the psychiatrist at the Special Needs Clinic, says, ''17 and 18 years old. One wants to be in the Armed Forces, and the other wants to be a pilot. Given their status, they've heard plenty about issues related to their having sexual partners and how to remain safe. But now they're hearing about how they're not able to do something they want to do with their lives, and once again, H.I.V. is there.'' ''This epidemic just marches on,'' Arpadi says. ''You and I will go to our graves, and there will still be this terrible epidemic. But in this country we've effectively stopped transmission to babies, so now we have this sort of cohort of aging kids. And I really wonder how they're going to make any sense of their lives. Everyone before them died earlier on, and there's no more kids like them behind.''

Jonathan Dee is a novelist and a contributing writer for the magazine. His last article was about Christian video games.