Background. There is a high prevalence of childhood obesity in Malta. The aim of this research is to gain insight into the environmental drivers of childhood obesity in Malta, and identify opportunities for an environmental approach to obesity prevention. Methods. This thesis comprises: (i) a contextual analysis of childhood obesity and the policy response in Malta; (ii) an overview of systematic reviews to identify environmental components of effective prevention interventions; (iii) an assessment of Maltese television advertising; (iv) an environmental audit of the food and built environment; (v) semi-structured interviews and focus groups with key informants; and (vi) microsimulation modelling to forecast the future health and economic burden of obesity in Malta. Results. Numerous environmental factors at multiple levels deter healthy dietary and physical activity behaviour among Maltese children. These include an obesogenic built environment that provides few opportunities for play or active transport, and a food environment characterised by easy access to, and heavy promotion of, energy-dense foods and beverages. The contextual analysis and environmental audit revealed several obesogenic aspects of the environment in Malta, such as substantial promotion of food high in fat, sugar and salt to children on local TV channels and a price premium for certain healthy food options in grocery stores. Thematic analysis of qualitative data revealed numerous barriers to healthy behaviours for Maltese children, including parental concerns about traffic hazard leading to restricted physical activity, and familal dietary patterns which encourage over-consumption of food. Interviews with food industry and public health actors also highlighted ‘framings’ of obesity that closely matched those described in the international literature. Microsimulation modelling illustrated the substantial financial savings and reductions in noncommunicable disease incidence if population weight reduction were to be achieved. Conclusions. An obesogenic environment underlies the problem of childhood obesity in Malta. The socio-ecological approach used in this research highlighted key areas for intervention and illustrated the importance of taking context into account when designing national obesity-prevention efforts.