Peer support interventions have mostly neglected the domain specificity of intervention effects. In two studies, the present investigation examined the domain specificity of peer support interventions targeting specific domains of self-concept. In Study 1, participants ("n" = 50) who had received an academically oriented peer support intervention on verbal subject matter improved significantly in verbal self-concept--but not other areas of self-concept--as compared with a control group that had not participated in the intervention. In Study 2, participants ("n" = 53) who had received a socially oriented peer support intervention that focused on interpersonal skills and communication improved significantly in same-sex relations self-concept--but not in other areas of self-concept--as compared with the control group. Hence, there is a compelling need for reconceptualizing peer support into academic and social domains in terms of domain specificity. (Contains 2 tables.)