This study evaluated the effects of self-control skills intervention to prevent smoking with middle school subjects. Informed and consenting subjects were pretested, then by school were randomly divided into three conditions: experimental, placebo, and test-only control. Experimental condition subjects received self-control skills intervention covering self-instruction, self-reinforcement, problem solving, and interpersonal communication. Placebo condition subjects received a discussion-oriented intervention employing health education methods to prevent smoking. Results at 15-month follow-up indicated that self-control and placebo condition subjects, relative to control condition subjects, improved more on measures of health knowledge and nonsmoking intentions. Self-control skills subjects had better 15-month follow-up scores than subjects in the other two conditions on measures of communication, self-instruction, self-praise, cigarette refusals, and noncompliance to smoke. Self-control condition subjects reported less weekly cigarette smoking compared with placebo and control condition subjects at final follow-up.