Introduction & Objective: The prevalence of substance abuse among college students is increasing drastically and requires immediate skill-based substance abuse intervention such as assertive skills. The purpose of this study was to develope the healthy behavior to change the subjective norms of students in order to decrease their tendency towards substance abuse.

Materials & Methods: A pre and post nonequivalent control group design study carried out on college students. A total number of 140 students were selected through randomized cluster sampling and randomly assigned to the intervention (n=70) and the control (n=70) groups. The data-gathering tool consisted of a self-report questionnaire assessing the variables of moral , descriptive , and injunctive norms. After the diagnostic evaluation, assertive skills promoting program was applied to persuade the participants against substances abuse. Respondents in the control and experimental groups completed questionnaires at baseline and 2 months after the intervention.

Results: The result showed that educational manipulation had significant effect on intervention group’s average response for moral norms (t= -3.36, P<0.001), descriptive norms (t= -3.07, P<0.003), and injunctive norms for persuading substance abuse (t=-3.79, P<0.000). Conclusion: These findings suggest that assertive skills training would be an efficient tool in drug abuse prevention programs among adolescents that should also be included in the comprehensive school health programs.