Childhood obesity is a major global concern but there is little evidence for effective childhood obesity prevention strategies. People of South Asian origin are a specific target group for obesity prevention as they are vulnerable to cardiovascular health effects of obesity. This thesis explores the contextual influences on the development of childhood obesity by presenting two studies; a quantitative analysis of routine datasets explores the association between the school physical activity environment and obesity in children, and a qualitative study explores the beliefs of South Asian community members and other stakeholders about the causes of childhood obesity and potential interventions to prevent it. A process of development of a childhood obesity prevention programme tailored to South Asian communities, guided by the MRC framework for complex interventions is described. The contextual information from the stakeholder focus groups is central to this process. Finally, this thesis examines the potential consequences of obesity in South Asian children by exploring its association with body image. Understanding the psychosocial consequences of obesity in target communities will enable future interventions to be appropriately designed. The findings of this thesis highlight the importance of understanding the cultural context with respect to childhood obesity causes, consequences and intervention.