The best current studies sampled homeless people from shelters, from the streets, and occasionally from jails and also used multiple or standardized measures of alcohol and other drug problems. The analyses suggest that at least 50 percent of the homeless people in the United States have significant current problems with alcohol, other drugs, or both. Homeless men are several times more likely than homeless women to have alcohol problems, but this gender difference does not consistently exist among abusers of other drug abusers. Homeless people with alcohol or other drug problems appear to have a tougher time on the street and in the shelters than other homeless people, particularly in their incidence of serious health problems. People with alcohol and other drug problems are disproportionately represented among the homeless. Being bad tenants, exhausting the capacities of any relatives and friends and resources, and being poor are all factors. Research demonstration efforts funded by the National Institute on Alcohol Abuse and Alcoholism in consultation in consultation with the National Institute on Drug Abuse are focusing on community-based treatment for persons with alcohol and other drug problems who are homeless or at imminent risk of becoming so. Three particularly challenging issues in designing and implementing these programs are accessibility, the need for comprehensive and continuous care, and housing. Reference notes and chart summarizing the demonstration grants