The article reviews the epidemiology of major depression across cultures, focusing on prevalence, course, socio-demographic correlates, and societal costs. Major depression is estimated to be a common disorder, with lifetime prevalence estimates ranging from 1.0% to 19.0% across different countries. The 12-month prevalence estimates range from 0.3% to 10%. Cross-national data show consistent socio-demographic correlates such as gender, age, marital status, and socioeconomic factors. The illness course is characterized by chronic-recurrent episodes, with a median age of onset typically in the early to mid-20s. The adverse consequences of major depression include difficulties in role transitions, reduced role functioning, increased risk of secondary disorders, and elevated mortality rates. The article also discusses the impact of depression on education, marital stability, childbearing, employment, and financial success. Despite the high prevalence and societal burden, treatment rates remain low in many countries. The authors suggest that expanded depression treatment could be cost-effective and beneficial for individuals and society.The article reviews the epidemiology of major depression across cultures, focusing on prevalence, course, socio-demographic correlates, and societal costs. Major depression is estimated to be a common disorder, with lifetime prevalence estimates ranging from 1.0% to 19.0% across different countries. The 12-month prevalence estimates range from 0.3% to 10%. Cross-national data show consistent socio-demographic correlates such as gender, age, marital status, and socioeconomic factors. The illness course is characterized by chronic-recurrent episodes, with a median age of onset typically in the early to mid-20s. The adverse consequences of major depression include difficulties in role transitions, reduced role functioning, increased risk of secondary disorders, and elevated mortality rates. The article also discusses the impact of depression on education, marital stability, childbearing, employment, and financial success. Despite the high prevalence and societal burden, treatment rates remain low in many countries. The authors suggest that expanded depression treatment could be cost-effective and beneficial for individuals and society.