In 1994 and 1995, the Substance Abuse and Mental Health Services Administration and the Center for Substance Abuse Prevention funded 123 community coalitions throughout the United States. These programs were evaluated in terms of factors that affected the coalition building process and community-based outcomes. The model for building coalitions consisted of such components as coalition structure, characteristics, capacity, and prevention activities. It was hypothesized prevention activities and community actions would influence drug abuse behavioral outcomes. The model was tested using data collected over a 3-year period covering 1996 to 1998 from coalitions that participated in the Community Coalitions Program. Evaluation results indicated coalitions that focused on prevention activities and community actions experienced community-based reductions in drug abuse and related health problems. The most important mechanism that seemed to drive the coalition building process involved the actions and activities implemented by the coalitions. 17 references, 2 tables, and 3 figures