One-year follow-up data from three seventh-grade cohorts of Project SMART were examined to assess the effects of two social psychology-based programs within each of six subgroups: males, females, Asians, blacks, Hispanics, and whites. The three cohorts (total N = 5,070) were those receiving curriculum or serving as controls as seventh-graders in 1982-1983, 1983-1984, and 1984-1985 school years. The outcome measures used were composite indices based on lifetime and recent use items for cigarettes, alcohol, and marijuana. The major analysis was ANCOVA on classroom means for the composite indices at post-test, using pretest classroom means for the indices as a covariate. The results showed clear prevention effects for females but not for males. Overall prevention effects were strongest for cigarette smoking, but were also evident for alcohol. Significant sex by program interactions, showing differential program effects for males and females, were found for cigarettes and marijuana, but not for alcohol. There was a nonsignificant trend suggesting that the programs were most effective for Asians and least effective for whites.