Note:  Correspondence concerning this article should be addressed to Barbara Gasteiger Klicpera, Department of Educational Psychology, University of Education Weingarten, Kirchplatz 2, D-88250 Weingarten, Germany. E-mail: email@example.com
Abstract: The effectiveness of a peer-mediation-program for third grade students (elementary school) was evaluated through a longitudinal study. The sample consisted of 262 students, 141 boys and 121 girls, drawn from thirty classrooms in fifteen elementary schools. There was one intervention and one control-class in each school. The evaluation was carried out through questionnaires which were filled out by all students and teachers before and after the intervention as well as one year later. The questionnaires comprise four scales to assess direct and indirect aggressive behavior, victimisation, and prosocial behavior. Results suggest that the impact of the intervention is gender-related. According to teachers' evaluations there was an improvement of prosocial behavior of boys in the intervention classes. In addition, they showed a decrease in direct and indirect aggression and victimisation. In contrast, teachers reported a deterioration of prosocial behavior as well as an increase in direct and indirect aggression among the girls.