This meta-analytic review examines the association between attachment during the early life course and social competence with peers during childhood, and compares the strength of this association with those for externalizing and internalizing symptomatology. Based on 80 independent samples (N = 4441), the association between security and peer competence was significant (d = 0.39, CI 0.32; 0.47) and not moderated by the age at which peer competence was assessed. Avoidance (d = 0.17, CI 0.05; 0.30), resistance (d = 0.29, CI 0.09; 0.48), and disorganization (d = 0.25, CI 0.10; 0.40) were significantly associated with lower peer competence. Attachment security was significantly more strongly associated with peer competence than internalizing (but not externalizing) symptomatology. Discussion focuses on the significance of early attachment for the development of peer competence versus externalizing and internalizing psychopathology.