The idea of a knowledge society has been raised over the last two decades but the transition to such a society has not been realized up to the present time, and discussion about a knowledge society has largely focused on a knowledge economy and information society rather than a mobilization to a knowledge society. These debates have, however, taken place before the rise of open data and big data and the development of an open data movement. The book considers the role of the open data movement in fostering transformation to a knowledge society. The characteristics of the open data movement include the strong conviction of the value of open data for society, attention to the institutional aspects of making data open in an inclusive way, and a practical focus on the technological infrastructure that are key in mobilizing a knowledge society. At the heart of any mobilization is an emerging open data ecosystem and new ways of producing and using data - whether 'born digital' data, digitized data, or big data - and how that data, when made openly available, can be used in a knowledgeable way by societal actors.