It has long been assumed that children and adolescents want to be with their peers and therefore make active efforts to engage with them. However, a sizable minority of youth avoid peers for internal reasons (e.g., anxiety, preferences for solitude) or because they are socially withdrawn. Although by definition, withdrawn youth tend to stay away from peers, they do interact and form relationships with peers. Yet most research assesses peers narrowly, focusing almost exclusively on youth who share the same gender and grade/school, leaving unanswered questions about which peers matter most. In this article, we highlight research findings that illustrate the very influential peer experiences of withdrawn children and adolescents, and we discuss emerging research on less frequently studied peers. By assessing peers more broadly, we contend, knowledge about the importance of peers to withdrawn youth will extend from same-gender and same-school contexts to the larger social milieus they inhabit.