The current study investigates determinants of young Australians' pro-environmental intentions and actions. Two samples of young people took part in the research: 12-17-year-olds (N = 1529) currently in secondary schooling and 18-24-year-olds (N = 2192) in post-secondary schooling or workforce. All participants completed an online "Youth and the Environment Survey" that assessed perceived responsibility of community and government to protect the environment, locus of control, environmental concern, self-reported environmental knowledge, pro-environmental intentions, pro-environmental behaviour and environmentally harmful behaviour. Attributing greater responsibility to the community was related to more positive environmental intentions and actions, whereas, attributing greater responsibility to the government for environmental protection was related to more negative environmental intentions and behaviour. In addition, young people with higher environmental concern and knowledge, and a more internal locus of control in relation to the environment, reported stronger pro-environmental intentions and behaviour, and less environmentally harmful behaviour. (Contains 5 tables.)