School mediation (or peer mediation) is an effective practice for dealing with cases of in-school violence and bullying. According to the results of this retrospective research, conducted in High-Schools of the Municipality of Fyli (Athens metropolitan area, Greece), school mediation programmes contribute to: activating students wishing to help their classmates, taking responsibility and developing social/communication skills of the students involved. At the same time, it is important to point out the substantial gender differentiation in attitudes both towards incidents of in-school violence and bullying, but also to school mediation programmes. Finally, the positive response of students, who participate voluntarily beyond ordinary school hours in these programmes, is a demand for a school that responds to students’ needs.