This study presents data on the prevalence, impairment, and demographic correlates of DSM-IV major depressive episodes (MDE) in 18 countries across the World Mental Health (WMH) Survey Initiative. The average lifetime prevalence of MDE was 14.6% in high-income countries and 11.1% in low- to middle-income countries, while the 12-month prevalence was 5.5% and 5.9%, respectively. Functional impairment was associated with the recency of MDE, and the female-to-male ratio was approximately 2:1. In high-income countries, younger age was linked to higher 12-month prevalence, whereas in several low- to middle-income countries, older age was associated with a greater likelihood of MDE. The strongest demographic correlate in high-income countries was being separated from a partner, while in low- to middle-income countries, being divorced or widowed was the strongest correlate. MDE is a significant public health concern globally, strongly linked to social conditions. The study found that cross-national differences in MDE prevalence estimates may be influenced by variations in the optimal threshold for detecting clinical cases. The results showed that the ratio of highest to lowest screen-positive rates across countries was similar to the ratio of highest to lowest conditional prevalence rates among screen-positives. The study also found that MDE was associated with substantial impairment, with the degree of impairment varying by country. The association between prevalence and impairment was positive, with higher prevalence linked to higher impairment. The study also found that gender, age, and marital status were consistently associated with MDE, with women having a twofold increased risk compared to men. The association between age and MDE varied by country, with younger age associated with higher prevalence in some countries and older age in others. Marital status was a consistently significant correlate of MDE, with being separated, divorced, or widowed associated with increased risk. The study also found that income was significantly associated with MDE in high-income countries but not in low- to middle-income countries. The findings highlight the importance of considering cross-national differences in prevalence estimates and the need for further research to investigate the combination of demographic risk factors that are most strongly associated with MDE in specific countries.This study presents data on the prevalence, impairment, and demographic correlates of DSM-IV major depressive episodes (MDE) in 18 countries across the World Mental Health (WMH) Survey Initiative. The average lifetime prevalence of MDE was 14.6% in high-income countries and 11.1% in low- to middle-income countries, while the 12-month prevalence was 5.5% and 5.9%, respectively. Functional impairment was associated with the recency of MDE, and the female-to-male ratio was approximately 2:1. In high-income countries, younger age was linked to higher 12-month prevalence, whereas in several low- to middle-income countries, older age was associated with a greater likelihood of MDE. The strongest demographic correlate in high-income countries was being separated from a partner, while in low- to middle-income countries, being divorced or widowed was the strongest correlate. MDE is a significant public health concern globally, strongly linked to social conditions. The study found that cross-national differences in MDE prevalence estimates may be influenced by variations in the optimal threshold for detecting clinical cases. The results showed that the ratio of highest to lowest screen-positive rates across countries was similar to the ratio of highest to lowest conditional prevalence rates among screen-positives. The study also found that MDE was associated with substantial impairment, with the degree of impairment varying by country. The association between prevalence and impairment was positive, with higher prevalence linked to higher impairment. The study also found that gender, age, and marital status were consistently associated with MDE, with women having a twofold increased risk compared to men. The association between age and MDE varied by country, with younger age associated with higher prevalence in some countries and older age in others. Marital status was a consistently significant correlate of MDE, with being separated, divorced, or widowed associated with increased risk. The study also found that income was significantly associated with MDE in high-income countries but not in low- to middle-income countries. The findings highlight the importance of considering cross-national differences in prevalence estimates and the need for further research to investigate the combination of demographic risk factors that are most strongly associated with MDE in specific countries.