The physical environment that people are exposed to greatly influences their diet-related decisions and behaviours. The current obesity-promoting environment is typified high availability, accessibility and promotion of less-healthy food and drinks. The ‘toxic’ environment is leading to poorer health outcomes, particularly within the youngest generations of Australians. The overarching aim of the research presented in this thesis was to determine the drivers of food purchasing and consumption behaviours of young people, develop and test approaches for defining food environments in tertiary education settings and identify best-practice intervention strategies for improving young people’s dietary behaviour through environmental changes.