Eco-communities, a form of housing that focuses on both a sense of community and sustainable behaviour, have been established in large numbers in Denmark in recent years, and interest of this way of living sustainable everyday lives is only increasing. Based on insights from anthropological fieldwork in three Danish eco-communities, the chapter describes how the well-organised physical and social structures in eco-communities promote sustainable behaviour among residents. For instance, people are more self-sufficient when they produce their own food, and they share more when they become members of eco-communities. At the same time, however, it is also important to the residents to avoid being self-righteous or too idealistic and to also avoid interfering with other people’s choices about, for example, being vegetarian or joining communal dinners. The sustainable behaviour that takes place in eco-communities does not happen for exclusively idealistic reasons, it also happens on pragmatic grounds. Hence, a balance between sustainable practice, collective engagement, and individual freedom is crucial in order to ensure the liveability of eco-communities.