The study found that the single lesson improved general knowledge about tobacco and students' ability to identify appropriate refusal techniques; however, improvement in the intent not to smoke was not significant. This finding is explained by both treatment and control groups' high scores on intent to smoke just prior to the presentation of the lesson. According to the theory of Planned Behavior, three factors interact to influence behavioral intent: increasing knowledge, teaching about and practicing behavioral control skills, and changing normative beliefs that influence behavior. Normative beliefs about peer approval of smoking, peer smoking behavior, peer relationships, and assumptions about smoking prevalence in general were consistently related to the likelihood of smoking during adolescence. The lesson made no attempt to measure or change normative beliefs that underlie smoking. This evaluation obtained data from 789 fourth and fifth graders from the Plymouth-Canton, Michigan area. Students were instructed that it is illegal to buy cigarettes and that secondhand smoke is a health threat. They learned the name of the chemical that causes smoking addiction, to identify the three major components of tobacco smoke, to identify the diseases caused by long-term smoking, and to identify recommended actions to refuse smoking. They had the opportunity at the end of the lesson to express the intent not to smoke. In order to test the effectiveness of the program, participants were assessed just before the program and immediately after the program, and 6 weeks later. The 704 participants in the lesson were compared with a preselected comparison group (n=85) that was also given a pretest and a 6-week posttest. 3 tables, 3 figures, and 30 references