Using 50 effect sizes from both published and unpublished studies (team n = 3,198), we provide meta-analytic support for the positive relationship between shared leadership and team performance. Employing a random effects model, we found that the theoretical foundation and associated measurement techniques used to index shared leadership significantly moderated effect size estimates. Specifically, as compared to studies that conceptualized and employed assessments of overall shared leadership from members (i.e., an aggregation approach), network conceptions and measures of shared leadership evidenced higher effect sizes. Both network density and (de)centralization approaches to the study of shared leadership–performance relations exhibited significant and higher effect sizes than did the aggregation-based studies. Analyses also revealed lower average effect sizes when the sample studied was in the classroom/lab as compared to the field. Task complexity significantly moderated the shared leadership, with lower effect sizes observed with more complex tasks. No significant influence of team task interdependence was observed. We highlight the relative value of employing social network theories and measures as compared to aggregate theories and measures of shared leadership. Directions for future research and application are discussed.