This paper describes a community-based approach to delinquency prevention utilizing indigenous nonprofessionals as behavior change agents. Adult residents in two Model Cities communities served as "buddies" of youth referred for behavior and academic problems. The principles and techniques of behavior modification were used in the training of nonprofessionals as change agents and in the treatment of youth in the project. The program evaluation includes an analysis of the various treatment techniques employed. The results indicate that school attendance increased with application of social and material rewards, while other problem behavior was reduced. The findings suggest that reinforcement is a crucial ingredient in the behavior change process. (Author/SES)