The new high school intervention integrated three approaches: attitude-behavior change strategies derived from social psychological research on dissonance, self-perception, values, social norms, and commitment; organizational/cultural change strategies using student- driven participatory planning and multilevel change methods; and mobilization strategies adapted from the National Cancer Institute-funded Community Intervention Trial for Smoking Cessation (COMMIT). A comprehensive implementation evaluation used direct observation, multiple sources of self-report, program records, and cost data to assess the relationships between implementation, outcome, and cost- effectiveness; to provide direct measures of training and mobilization effects; and to develop feasible implementation evaluation methodology for future diffusion studies.