In describing the research on effectiveness, the report finds that the causes of substance abuse include factors at all levels of society, most prevention programs have focused only on the individual, and comprehensive programs that address a number of factors influencing drug use hold the most promise for prevention. Programs designed exclusively to impart knowledge have not proven effective in changing substance-abuse behavior. Programs to change beliefs have not yet been adequately evaluated. Evidence about programs' effectiveness in meeting social or psychological needs is mixed. Programs that focus on the family have promise, particularly if they are successful in reaching dysfunctional families. Schoolwide strategies show some success, but communitywide efforts are difficult to evaluate. Recommendations derived from the evaluations pertain to the planning and implementation of coordinated school and communitywide prevention efforts; broad-based school initiatives; the development of stronger linkages between theory, program activities, and evaluations; and the targeting of high-risk youth and their parents. A survey of the Federal Government, States, and local school districts found that they are actively engaged in efforts to prevent drug use by school-aged children. Appended survey instruments and methodological information