This meta-analysis assessed efficacy of cognitive-behavioral interventions in preventing anxiety symptoms. A systematic review identified 15 independent pretest-posttest randomized or quasi-randomized efficacy trials for analysis. At posttest, intervention groups demonstrated significantly greater symptom reduction compared to control groups resulting in weighted mean effect sizes (Hedges' g) of 0.25 for general anxiety, 0.24 for disorder-specific symptoms, and 0.22 for depression after the removal of outliers. These effects appeared to diminish over 6- and 12-month follow-up. Exploratory moderator analyses indicated that individually administered media interventions were more effective than human-administered group interventions at preventing general anxiety and depression symptoms. Implications of current findings are discussed with attention to existing gaps in the literature.