The establishment of AIDS hospitals and AIDS units within hospitals has been controversial. Unlike other specialty care, AIDS care arrangements were initially developed as much to segregate AIDS patients from other patients and staff as to provide the best possible care. Ten years after many of these units opened, little evidence was available about whether the benefits of aggregating AIDS patients outweighed the potential hazards of segregating people from the mainstream of hospital care. This Issue Brief describes a national study to determine how different organizational settings affect the outcomes of inpatient AIDS care.