OBJECTIVES: Climate change and energy vulnerability present significant challenges for the development and sustainability of our communities. The adverse effects will most likely impact on those already experiencing poverty, as energy and food costs will rise, thus increasing inequalities in health. Transition town initiatives seek to build cohesive sustainable communities to prepare for a future with limited oil and a changing climate. Increasingly, public health practitioners are interested in the role of transition towns as a community development initiative, and their potential to support the wider public health agenda. Health impact assessment (HIA) is an evidence-based process that aims to predict the positive and negative impacts of a strategy, proposal or development. The HIA process provides an opportunity to promote sustainable communities by ensuring that new strategies and developments are considered in the context of their contribution to the health and well-being of local populations. The aim of this study was to use an HIA to examine the potential health and well-being benefits of two related transition town initiatives. STUDY DESIGN: A rapid HIA to consider the potential lifestyle changes and health and well-being impacts of Transition Together/Transition Streets (TT/TS) projects. METHODS: An HIA template was used to assess key documents related to the TT/TS initiatives and those related to the characteristics of the community. Additionally, meetings with 12 key informants (four involved in TT/TS and eight purposively selected for their local knowledge) were held using the HIA template to focus the discussion. RESULTS: The findings highlight the associated lifestyle changes such as increased physical activity and healthy eating, and possible social and well-being benefits of engagement in such an initiative. Engagement may be limited to those already concerned about environmental issues. CONCLUSION: This paper illustrates the important links between transition towns and the wider public health agenda, and demonstrates how an HIA can be applied to a community-based initiative. It provides a means by which transition town initiatives can demonstrate health and well-being benefits, whilst raising concerns about inclusivity and equity.