Socially withdrawn children are at increased risk for various maladaptive outcomes. One intervention suggested to mediate these outcomes is the use of peermediated social skills training. However, little research supports its use with socially withdrawn children; even less research has investigated the role of peer mediators in the generalization of treatment effects. The purpose of this study was to evaluate a generalization training package on the generalization of socially withdrawn students and their peer mediators' interactions. This study compared the effectiveness of various procedures in a peer-mediated intervention on the generalization of prosocial interactions with socially withdrawn students and examined how students' perceptions of social support, bullying experiences, and intervention acceptability changed as a result of the peer-mediated social skills training intervention. Results indicated that the socially withdrawn participants engaged in more prosocial behavior following the intervention and that it generalized to a highly unstructured, novel setting with multiple students.