Research shows that conflicts in schools cannot be resolved by constructive and peaceful means and teachers cannot support students sufficiently. To solve this problem, the Negotiation and Peer Mediation Training Program was experimented on the fourth-, fifth- and sixth-grade students in this study aiming to examine the effects of the Negotiation and Peer Mediation Training Program on conflict resolution and problem-solving skills. The study was conducted on 44 students attending the "Children's University" summer school. The research was carried out in the pretest-posttest design without control group. The training program consisting of 18 activities was implemented. The students were subjected to "Conflict Resolution Skills Scale" and "Problem Solving Inventory for Children" before and after the program. The pretest and posttest scores of both instruments total tests and subscales were analyzed with dependent samples t-test. It was observed that the training program was not effective on problem solving but reduced "obliging" and "avoiding" behaviors. Results achieved in the other subscales of the Conflict Resolution Skills Scale were not coherent with the literature. Based on the research results, it can be argued that the Negotiation and Peer Mediation Training mitigated the avoiding and obliging behaviors which do not serve a peaceful resolution.