In 2 meta-analyses on gender differences in depression in nationally representative samples, we advance previous work by including studies of depression diagnoses and symptoms to (a) estimate the magnitude of the gender difference in depression across a wide array of nations and ages; (b) use a developmental perspective to elucidate patterns of gender differences across the life span; and (c) incorporate additional theory-driven moderators (e.g., gender equity). For major depression diagnoses and depression symptoms, respectively, we meta-analyzed data from 65 and 95 articles and their corresponding national data sets, representing data from 1,716,195 and 1,922,064 people in over 90 different nations. Overall, odds ratio (OR) = 1.95, 95% confidence interval (CI) [1.88, 2.03], and d = 0.27 [0.26, 0.29]. Age was the strongest predictor of effect size. The gender difference for diagnoses emerged earlier than previously thought, with OR = 2.37 at age 12. For both meta-analyses, the gender difference peaked in adolescence (OR = 3.02 for ages 13–15, and d = 0.47 for age 16) but then declined and remained stable in adulthood. Cross-national analyses indicated that larger gender differences were found in nations with greater gender equity, for major depression, but not depression symptoms. The gender difference in depression represents a health disparity, especially in adolescence, yet the magnitude of the difference indicates that depression in men should not be overlooked.