The greatest strain on public health is the continued increase in non-communicable diseases (NCDs) (World Health Organization, 2018). 83.6% of NCDs mortality is caused by exposure to factors in our environment that are amenable to policy interventions (Rappaport, 2016). A key risk factor of NCDs relates to food related behaviours. Public health policies, which are in large based on education or knowledge transfer, have not generated a significant impact on poor nutrition and obesity. A key challenge is the complexity of factors that affect obesity related behaviours. Effective interventions require a comprehensive and holistic understanding of the interplay of these factors in driving food related behaviours. Few attempts have been made to systematically link and triangulate different sources of socio-economic, behavioural, biological and exposure to the built environment data and analyses that can inform change that will affect public health. Past traditional approaches almost exclusively relied on partial separate datasets, targeting specific groups of the population with one off interventions, only derived from narrow research hypotheses. As such are however quite limited in use for the development of behaviour change interventions with a sustained impact over time. Those approaches fail to capture the dynamics of behaviours that shape individual’s health risky behaviours and their impact on health, and how these are influenced by complex interactions with the environments. Our proposed approach is to leverage a unique longitudinal dataset with linked data on individual’s health outcomes, behaviours and characteristics, and environmental mapping capturing the multilevel determinants of behaviours to develop a better understanding of nutrition determinants and design, implement and evaluate behavioural interventions in school food environments in Sri Lanka. Nearly 29% of the adults in Sri Lanka are overweight or obese, 73% of the population do not consume the sufficient servings of fruits and/or vegetables per day (World Health Organization, 2015). Only 14.7% of children (average boys and girls) eat five or more servings of fruit and/or vegetables per day (Darfour-Oduro et al, 2018). Also, there has been a constant increase in children with comorbidities such as high blood pressure, insulin resistance and dyslipidaemia which are often caused by obesity (Wickramasinghe et al., 2013). It is also important to target children as obesity in childhood has been found to impact lifetime outcomes such as adult obesity, human capital (school proficiency and cognitive skills), and social outcomes (social exclusion and stigma) (Bhadoria et al., 2015). To do so we will leverage the infrastructure developed in the Global Health Research Unit for Diabetes and Cardiovascular disease (GHRU) cohort study that has been gathering environmental and surveillance measures within ~250 surveillance sites of an established South Asia Biobank collected for adults. We propose to complement the adult surveillance data with data on children and link it to environmental mapping data at individual level (using residence and school location) including location, provision, and promotion of food and physical activity facilities in each surveillance site and covers 200-meter buffer from the school.