The plight of the homeless in New York City and other urban areas has become the focus of increasing attention. In an effort to clarify and understand the problems of the homeless, the authors studied the demographic characteristics, psychiatric diagnoses, histories, and dispositions of 100 homeless patients treated at Bellevue Psychiatric Hospital's emergency service. The most striking finding was that 96.6 percent of the sample had had a previous psychiatric hospitalization. Seventy-two percent of these homeless patients were diagnosed as suffering from schizophrenia; the second most common diagnosis was personality disorder, which accounted for 13.3 percent of the sample. The authors discuss other demographic findings of their study and explore the roots of the problem of homelessness, review the psychiatric literature on the subject, and delineate some of the unique treatment needs of this population.