PURPOSE: This study was done to develop a school-based anger management program (SAMP) of 4 sessions and examine its effects on the anger, anger expression, psychosomatic responses, psychosocial responses, and immunologic responses in adolescents. METHODS: A quasi-experimental study using a nonequivalent control group, pre-post design with repeated measures was used. Chi-square test, t-test, paired t-test, and Fisher's exact test were used to analyze the data. RESULTS: There were no differences between the experimental and control groups in outcome variables except for lymphocytes. However, following additional analyses, statistically significant differences by time point were observed for pain sensitivity, T cell, Helper T (Th) cell, Suppressor (Ts) cell and Natural Killer (NK) cell post-treatment, entrapment and psychosomatic symptoms at the 4-week follow-up, and resilience at the 10-week follow-up for the experimental group. CONCLUSION: Although some modifications in contents and administration will be required to increase the effectiveness of the program for anger management, SAMP can be used to promote anger management ability in adolescents.