We use the study of changes towards sustainable development in rural Europe as a means of illuminating the shape and dynamics of European knowledge society more generally. We define a knowledge society as one which contains not just one but a plurality of knowledges, expert and lay. These range from the scientific, economic, administrative, and managerial to local, practical, and ecological knowledge, traditional repertoires, trial and error or experientially-based discoveries. We further define sustainable development as a knowledge-based set of practices, within which the expert form of knowledge has been dominant, but to which non-expert forms may make a significant contribution. We seek to identify the dynamics of these different forms of knowledge, and their functioning in relation to economy and society, through case studies in 12 different European countries of rural development projects oriented towards increasing sustainability.