This study was carried out to compare the effects of self-determination skills training and parent management training on the externalizing behavior problems of students. This quasi-experimental research had a pretest-posttest, control group design. To achieve research goals, 45 students with externalizing behavior problems who were identified through Child Behavior Checklist (CBCL) and via random multi-stage cluster sampling method were selected and randomly assigned to two experimental and one control group. The self-determination skills and parent management training programs were administered to both experimental groups (one group of students and another group of mothers) in 10 sessions. Child Behavior Checklist (CBCL) was completed by participant parents before and after the intervention. Results of multivariate covariance analysis showed that both self-determination training and parent management training had positive effects on reducing externalizing behavior problems, aggressive and rule-breaking behaviors. Comparing the effect of self-determination skills and parent management training, the results showed that self-determination training was more effective in reducing externalizing behavioral problems and rule-breaking behaviors. The results demonstrated that there was no difference between the effectiveness of the two interventions regarding aggressive behavior. The study's findings can be fruitful for therapists and counselors concerning the selection of the appropriate type of interventions.