In 1985, the New York City Health Care for the Homeless Program began providing health care and social services to homeless people. The program seeks to provide care to those homeless people with the least access to services, reaching out to them in soup kitchens, shelters, and hotels. This paper summarizes what has been learned since 1985 about the special needs of homeless people and about the difficulties of providing services to this disaffiliated and vulnerable population. The report contains four principal sections. The first section, "Who Are America's Homeless?" identifies the major groups of single adults, families, and youth. The second section, "One Response: The New York City Health Care for the Homeless Program," describes the design and history of the program, its biggest challenges, and the support of the outreach staff. The third section, "Holes in the Safety Net," reviews obstacles to providing care, including site limitations, reluctance to receive care, staffing changes, institutional aversion, and lack of facilities. The fourth section, "Implications for Public Social Policy," examines issues underlying homelessness, including racism, mental illness, substance abuse, HIV-related illnesses, and housing needs. The paper includes statistical data in six tables and charts and a list of 17 references. (AF)