School coexistence is an educational challenge and the implementation of mediation is an essential tool for managing conflicts and improving interpersonal relationships. However, there are few studies that show its impact and even fewer that take into account students' perceptions. In this ex post facto research, we are interested in finding out the ratings provided by students from Spanish secondary schools where mediation takes place, paying special attention to those students who mediate conflicts. Specifically, the aim is to highlight the strengths and weaknesses of mediation from the perspective of the participating students and to detect any significant differences depending on whether or not the student is a mediator, their gender, the educational stage and school year. To this end, 1,198 students answered a validated questionnaire developed ad hoc. As general results, the descriptive and inferential analyses show that there is an overall positive assessment of mediation, even though the students who are mediators provide higher ratings. In addition, there are hardly any differences between boys and girls, ratings are generally more positive in the compulsory secondary school stage and, more specifically, in the first years of secondary school. Regarding initiatives that could strengthen school mediation practices, it is necessary to provide information on mediation services in the education centres, train all students and expand the scope of mediation.