The study investigated efficacy of rational emotive behavioural therapy and cognitive behavior therapy in reducing aggressive behavior among secondary school students. The design adopted for the study was a quasi-experimental. The population for the study was 100 participants who showed tendency towards developing aggressive behaviour. Buss-Perry Scale for Aggressive Behaviour (BSAB) was used to collect data for this study. Two research questions as well as two hypotheses were formulated for the study. The data collected were analyzed using mean and standard deviation statistics for the research questions while the hypotheses were tested with a paired t-test statistics. The data analyzed revealed that, REBT and CBT is an effective and rewarding technique in the treatment of aggressive behavior among secondary school adolescents. Based on the findings, it was recommended that; Aggressive students should be encouraged to receive psychotherapeutic trainings like REBT and CBT. Counsellors should be well equipped in this area of using this two therapeutic skills. Also, Parents, significant others, stakeholders in the school, andadult members of the family should be encouraged to maintain and live a peaceful and healthy family relationship.