Considerable work has demonstrated significant impairment in social functioning for children with attention deficit/hyperactivity disorder (ADHD). The social functioning profiles of children with ADHD are marked by impairments across diverse domains as they tend to experience greater rates of peer rejection, have lower levels of social skills, and have impaired social cognitions. The purpose of this study was to (a) quantitatively examine the association between ADHD and deficits across several domains of social functioning (peer functioning, social skills, social information processing), (b) examine differences in the magnitude of such associations, and (c) examine the effect of potential moderators. A meta-analysis of 109 studies (n = 104,813) revealed that children with ADHD have the most impairment within the peer functioning domain (weighted effect size [ES] r = .33) followed by significantly smaller effects within the social skills (weighted ES r = .27) and social information-processing domains (weighted ES r = .27). When examining potential moderators, results revealed that the association between ADHD and deficits within the social skills domain was weaker among studies that controlled for co-occurring conduct problems (CP). Studies that utilized sociometric and teacher reports of peer status reported the largest effects within the peer functioning domain. In addition, studies that utilized the "gold standard" approach to diagnosing ADHD documented the largest effects within both the social skills and peer functioning domains. Last, studies utilizing younger samples revealed the largest effects for deficits within the peer functioning domain. Theoretical and clinical implications are discussed.