An experimental peer leadership curriculum in which older adolescents counsel younger peers in how to resist social pressures toward smoking has been developed for experimental study. In a California site near Stanford University one cohort of 7th grade students (n equals 300 plus) in the 1977-78 school year was selected to receive the program, while two matched cohorts (n equals 300 plus) were selected as control units. Baseline and follow-up surveys of smoking and other pertinent variables are being conducted periodically in all three cohorts. Results of the first year of follow-up reveal a significantly lower rate of onset of smoking among students receiving the program, with some evidence of generalization to other substance use and support for the hypothetical model on which the intervention is based. Replications of that work are underway in diverse populations in two sites near Boston.