Child and adolescent anxiety disorders (ADs) contribute to impairment in social functioning and peer relationships, exacerbating anxiety and related difficulties. The extent to which the AD treatment with the strongest evidence-base, cognitive-behavioral therapy (CBT), improves social functioning and peer relationships is unclear. In this article, we report results of the first systematic narrative review of this topic. Randomized clinical trials of CBT for child and/or adolescent ADs were included if they used at least one measure of social functioning or peer relationships as a treatment outcome. Sixteen studies met our inclusion criteria. From each study, we extracted the sample characteristics, treatment arms, social and/or peer outcome measures, and statistical findings. Results show that social functioning and/or peer relationships improved over time in the majority of studies, highlighting an important aspect of treatment efficacy beyond anxiety reduction. There were also several treatment-specific effects, but considerable variability across studies’ samples, methods, and findings, makes it difficult to draw firm conclusions about which specific treatments improve specific outcomes. We recommend next steps for research to reconcile these findings, including improved operationalization and standardization of social and peer outcomes, and research on treatment specificity and mechanisms.