OBJECTIVE: To examine the association between body mass, mental disorders, and functional disability in the general population of 6 European countries. METHOD: Data (n = 21 425) were derived from the European Study on the Epidemiology of Mental Disorders (ESEMeD). The third version of the Composite International Diagnostic Interview was administered to assess mental disorders (mood, anxiety, and alcohol disorders) according to the Diagnostic Statistical Manual of Mental Disorders-fourth edition, body mass index (BMI) (kg/m(2), based on self-reported height and weight), and functional disability in the previous 30 days, assessed with the World Health Organization Disablement Assessment Scale-second version. RESULTS: About 3% of the respondents were underweight (BMI < 18.5 kg/m(2)), 53% had normal weight (BMI 18.5 to 24.9 kg/m(2)), 33% were overweight (BMI 25 to 29.9 kg/m(2)), and the remaining 12% met criteria for obesity (BMI >or= 30.0 kg/m(2)). Compared with individuals of normal weight, obese individuals were more likely to have mood (OR 1.3; 95%CI, 1.0 to 1.8) or more than one mental disorder (OR 1.4; 95%CI, 1.0 to 2.2). BMI had no impact on work loss days, whereas mental disorders had a considerable effect on work loss days. CONCLUSIONS: This is the first cross-national study investigating the role between BMI, mental disorders, and functional disability in the general population. Being overweight or obese is a common condition in the 6 ESEMeD countries. Although there is a moderate association between obesity and mental disorders, BMI did not independently influence functional disability.