Objective: To estimate the effectiveness of adherence-promoting psychological interventions for pediatric populations with chronic health conditions. Methods: A meta-analysis was conducted on 70 adherence-promoting psychological intervention studies among chronically ill youth using a weighted least squares approach and random effect model. Results: Medium effects sizes were found for the behavioral (mean d =.54, 95% confidence interval [CI] = 0.34-0.73, n = 10) and multi-component interventions (mean d =.51, 95% CI = 0.45-0.57, n = 46), while educational interventions displayed a small effect size with adherence (mean d =.16, 95% CI = 0.10-0.22, n = 23). Study designs incorporating pre-post comparisons yielded effect sizes approaching the medium range (mean d =.42, 95% CI = 0.36-0.48, n = 30). Conclusions: Behavioral and multi-component interventions appear to be relatively potent in promoting adherence among chronically ill youth. Recommendations for future research and methodological issues are presented.