The evaluation tested curriculum effectiveness in producing changes in student health knowledge, attitudes, practices, and self-reported priority health behaviors, such as cigarette smoking and use of alcohol or other drugs. The results are first presented using gain score analysis, a common technique for measuring the effects of education interventions. The data were then re-analyzed with linear models design to control for the possible confounding influences of school and student characteristics on study results. The last section examined the representativeness of the study population. Using the classroom as the unit of analysis, the study calculated average pretest, posttest, and gain scores for students' knowledge, attitudes, and practices. The effects size for increased knowledge of students exposed to THTM was large (0.84), and effect sizes for attitudes (0.50) and practices (0.42) were more modest.