Clean Up Australia Day is the country's largest community-based environmental annual event when participants work in teams to remove rubbish from their local environment. This article describes an interpretive study in which a sample of preservice primary teachers' (n = 30) responses to questions about their involvement in the event were evaluated to determine their developing knowledge and understanding about environmental and sustainability issues. The study evaluated a university assessment task for its ability to identify and challenge preservice primary teachers' views as consumers of manufactured products, environmental citizens, and future teachers. The data were drawn from students' written work that formed part of the assessment task. Results indicate that students found participation in this community event to be a signifcant, valuable part of their learning about the environment that contributed to their understanding about sustainability and highlighted the power of positive community participation as a force for good.