BACKGROUND: The determinants of common mental disorders in women have not been described in longitudinal studies from a low-income country. METHOD: Population-based cohort study of 2494 women aged 18 to 50 years, in India. The Revised Clinical Interview Schedule was used for the detection of common mental disorders. RESULTS: There were 39 incident cases of common mental disorder in 2166 participants eligible for analysis (12-month rate 1.8%, 95% CI 1.3-2.4%). The following baseline factors were independently associated with the risk for common mental disorder: poverty (low income and having difficulty making ends meet); being married as compared with being single; use of tobacco; experiencing abnormal vaginal discharge; reporting a chronic physical illness; and having higher psychological symptom scores at baseline. CONCLUSIONS: Programmes to reduce the burden of common mental disorder in women should target poorer women, women with chronic physical illness and who have gynaecological symptoms, and women who use tobacco.