The overall objective of the trial is to evaluate the cumulative effects of five program components that represent counteractive strategies on community influences on youthful drug use. These components include school, parents and family, community organization, health policy change, and mass media programs. Over 32,500 youth are evaluated annually with a self-report survey and a biochemical measure of smoking. Surveys are also administered yearly to about 150 community leaders and 7,200 parents. Three models have been used to develop the MPP as a multicommunity drug prevention project: matched funding, program implementation, and community organization. An evaluation of MPP process issues indicates that large-scale, longitudinal drug prevention projects require researchers and community programmers to be flexible about research and measurement design, development, refinement, and analysis. Further directions for community action research in the area of drug prevention are suggested. 7 references