The goal of the present study was to consider the associations between family functioning (parenting and family loneliness) and peer functioning in a sample of boys with ADHD (N = 110) and their mothers (N = 108) and fathers (N = 53). Results indicated that higher paternal warmth was associated with more peer acceptance, less peer rejection, and less problematic social behavior, but only for boys who reported low levels of family loneliness. In addition, more paternal power assertion was related to less peer acceptance, but only for boys who reported low levels of family loneliness. Maternal warmth and power assertion were not significantly related to boys’ peer functioning. We discuss these findings in the context of the processes by which parenting may affect the peer relationships of these children.