Objectives: This meta-analysis evaluates treatment effects for nonpsychotic major depression during pregnancy and postpartum comparing interventions by type and timing. Methods: Studies for decreasing depressive severity during pregnancy and postpartum applying treatment trials and standardized measures were included. Standardized mean differences were calculated for continuous variable outcome data. Results: Thirteen interventions reported positive effect sizes, one reported marginally positive effect size, one reported no effect, and the remaining reported marginally negative effect size. By type of treatment, medication with cognitive behavioral therapy (CBT; 3.871, p less than 0.001) and medication alone (3.048, p less than 0.001) reported largest effect size, followed by group therapy (CBT, educational, and transactional analysis; 2.045, p less than 0.001), interpersonal psychotherapy (1.260, p less than 0.001), CBT (.642, p less than 0.001), psychodynamic (.526, p = 0.014), counseling (.418, p = 0.014), and educational (0.100, p = 0.457). Postpartum implementation produced larger effect size (0.837, p less than 0.001) than implementation during pregnancy (0.377, p = 0.002). When medication interventions are excluded, postpartum effect size is 0.704 (p less than 0.001). Conclusions: Preliminary findings suggest medication, alone or with CBT; group therapy with CBT, educational, and transactional analysis components; interpersonal psychotherapy; and CBT produce largest effect sizes in this population among interventions tested. (Contains 3 tables.)