This research was carried out with a mixed research model to test the group psychoeducation program's effectiveness to improve psychological counselor candidates' forgiveness levels. In this research 2x3 (experiment / control groups - pre-test / post-test / follow-up test) quasi-experimental design was used. Participants of the study consist of 20 psychological counselor candidates; half of them are in the experimental group, and the other half of them are in the control group. The effectiveness of the psychoeducation program prepared by researchers was decided with Two Factor Variance Analysis for Repeated Measures and Bonferroni test. The research results indicated that the experimental group's level of forgiveness increased significantly after the group psychoeducation program compared to the control group, and this effect of the program was maintained until three months after the program. According to the interviews, the participants' gains from the program, the program's contributions, and the effective studies in the program were positive. It has been observed that the developed group psychoeducation program meets the needs of psychological counselor candidates in forgiveness.