BACKGROUND: Major Depressive Disorder (MDD) is a leading cause of disability worldwide. AIMS: To examine the: (a) 12-month prevalence of DSM-IV MDD; (b) proportion aware that they have a problem needing treatment and WHO want care; (c) proportion of the latter receiving treatment; and (d) proportion of such treatment meeting minimal standards. METHOD: Representative community household surveys from 21 countries as part of the World Health Organization World Mental Health Surveys. Results: Of 51 547 respondents, 4.6% met 12-month criteria for DSM-IV MDD and of these 56.7% reported needing Treatment. Among those who recognized their need for treatment, most (71.1%) made at least one visit to a service provider. Among those who received treatment, only 41.0% received treatment that met minimal standards. This resulted in only 16.5% of all individuals with 12-month MDD receiving minimally adequate treatment. CONCLUSIONS: Only a minority of participants with MDD received minimally adequate treatment: 1 in 5 people in high-income and 1 in 27 in low-/lower-middle-income countries. Scaling up care for MDD requires fundamental transformations in community education and outreach, supply of treatment and quality of services.