Substance abuse among teenagers has been spreading widely and become a serious social problem. However, teachers hardly realize its importance. Recently, substance abuse prevention programs show a tendency towards one time education. This study aims to research the effect of substance abuse prevention on high school students using the Life Skills Training Program. Two classes(36 students in the experimental group, 35 in the control group) at W High School in Daejeon were randomly sampled for this study from May to June 2002. Substance knowledge and attitude, problem solving, and assertiveness were examined as Pre and Post-Tests. The data was analyzed using frequencies, t-test, means, and covariance(ANCOVA). The results of this study were as follows； 1. Compared with the control group, substance knowledge in the experimental group was significantly improved(F＝176.317, P＝.000). And compared with the control group, substance attitudes in the experimental group were improved significantly.(F＝207.682, P＝.000). 2. Compared with the control group, cognitions to problem solving in the experimental group was significantly improved(F＝100.937, P＝.000). 3. Compared with the control group, assertiveness behaviors in the experimental group were increased significantly(F＝207.255, P＝.000). The study showed that Substance Abuse Prevention of High School Students was effective in improving substance knowledge and attitude, cognition to problem solving, and assertiveness behavior. Some suggestions based on the result are as follows； 1. Substance abuse preventive programs must be practiced properly and systematically with high school students in their regular classes. 2. Various preventive education programs must be developed for substance abuse where high school students can join in a community center, such as Community Welfare Center, Alcoholic Counseling Center, and Mental Health Center. 3. For the furthering of substance abuse preventive education, there must be continued research about not only students with problems of substance misuse and abuse, but also students without them. 4. There must be early determination of students with problems of substance misuse to be able provide school social workers with the opportunity for intervention.