This paper describes the Community Epidemiology Laboratory (CEL) of the Alcohol Research Group, a project focusing on the epidemiology of alcohol problems and community responses to those problems. Since 1980, a series of probability surveys have been conducted in the general population and in a wide range of health and social service agencies in a northern California county. The agency-based samples have included all agencies or representative samples of each system (alcohol treatment, drug treatment, mental health treatment, emergency rooms, primary health care, criminal justice and welfare) with probability samples of clients interviewed at intake. These studies have addressed questions regarding (1) the burden and epidemiologic description of alcohol problems in a community; (2) the relationship of alcohol to other health and social problems; (3) the influence of social policy on the constitution of services and care of individuals; and (4) health services issues of access and pathways to treatment. The project is designed for comparable analysis of studies with special focus on women and ethnic minorities. This paper provides an overview of the CEL, including its major research questions, overall design, sampling principles, methodological issues and measures. It highlights the main findings and discusses the limitations and advantages of such methodologies for further understanding alcohol problems in a community.