The purpose of present study was to examine the effect of friendship and relationship dimensions of the classroom environment on general and academic selfconcept. 784 male students aged 13-14 years from 30 classes in 11 schools in Tehran, Iran, participated in the study. A questionnaire was devised and used based on items from the Self-Description Questionnaire-II (Marsh in Self-description questionnaire-II: manual, Publication Unit, Faculty of Education, University of Western Sydney, Sydney, 1992), What Is Happening In this Class (Fraser et al. in Paper presented at the Western Australian Institute for Educational Research forum, Perth, 1996) and Classroom Environment Scale (Moos in Evaluating educational environments, Jossey-Bass, San Francisco, 1979) in addition to some new items. The relationship dimensions of classroom environment were significantly correlated with general and academic self-concept. Moreover, general self-concept mediated the relationship between friendship and academic self-concept. Pupils' academic norms had an effect on neither this correlation nor the correlation between general self-concept and academic self-concept. Finally, the correlation between general self-concept and academic self-concept was not effectively moderated by pupil-teacher relationship. Theoretical and practical implications of these findings are explained.