Objective: To assess attributions for overweight and the level of support for policy initiatives in Great Britain. Design: Cross-sectional. Respondents indicated their agreement (5-point scales: strongly disagree to strongly agree) to three potential causes of overweight (environment, genes, willpower) and five policies (free weight-loss treatment, taxing unhealthy foods, healthy lifestyle campaigns, food labelling, advertising restrictions). Setting: Data were collected as part of a computer-assisted, face-to-face Omnibus survey of adults (aged .15 years) from across Great Britain in April 2012 carried out by a market research company. Subjects: A population-representative sample of British adults (n 1986). Results: More people attributed overweight to the food environment (61 %) and lack of willpower (57 %) than to genes (45 %). Policy support was highest for healthy lifestyle campaigns (71 %) and food labelling (66 %), and lowest for taxing unhealthy foods (32 %). Food environment attributions were associated with higher support for all policies (P , 0?001). Genetic attributions were associated with higher support for free weight-loss treatments and healthy lifestyle campaigns (P , 0?001), but not other policies. Attributions to lack of willpower were not associated differentially with support for any policies (P . 0?01). Conclusions: Belief that overweight is caused by the food environment or genesboth seen as outside individual control -was associated with greater support for government policies to prevent and treat obesity. Improving awareness of the multiple causes of obesity could facilitate acceptance of policy action to reduce obesity prevalence.