Subject of the study are intentional communities with a strong emphasis on sustainable development. The study explores ecovillages and other socio-ecological communities in their role as lifestyle avant-gardes and as pioneers of sustainable development. Main interest is both the sustainability and the innovation potential of such communities. Chap. 1 provides a brief overview of the history of the ecovillage movement – not only, but especially the German movement. Chap. 2 uses international research to evaluate whether intentional communities live up to their ecological and social aspirations. In addition, a quantitative analysis of 129 communities situated in the German Sprachraum analyzes age, gender composition, consumption habits, preferred organisational structures and main areas of activity. Chap. 3 gives an overview of important functional properties. Chap. 4 discusses the social appeal, describes limitations of the approach and shows for which population groups a communal way of life is not a suitable lifestyle model. Chap. 5 gives policy recommendations.