In adolescence, peers represent key actors within individual social network. Given the relevance of peer connections and the growing literature examining them, the purpose of this article was to review, through a meta-analytic approach, studies on adolescent and youth peer relationships within the theoretical framework of attachment. First, we synthesized results of 44 studies focused on relationships between parent and peer attachment. Second, we summarized findings of 54 studies reporting gender differences on peer attachment. Third, we computed an overall effect for age differences on peer attachment documented in 19 studies. Main findings highlighted that parent attachment is moderately correlated to peer attachment; that females were significantly more attached to their peers than males; and that the correlation between age and peer attachment was not significant. This set of findings was confirmed examining both overall peer attachment as well as specific dimensions of attachment, such as trust and communication. Furthermore, since a significant heterogeneity was found across studies, we tested the effects of various categorical (i.e., year and language of publication, country, attachment measure) and continuous (i.e., mean age and percentage of females of the sample, number of items of the peer attachment scale) moderators related to characteristics of the study samples and designs. Implications of these findings for future research are discussed. A focus on cultural dimensions and on peer attachment processes would be worthwhile to address relevant research questions: How do peer relationships progressively become mature attachment relationships? How is this process shaped for individuals with different parent attachment histories?