This chapter outlines the overview of theories of collective action and social movements, followed by information about the empirical studies. It is based on studies of self-help and self-mobilization among marginal groups in Norway, starting with an action research project promoting and studying self-help and self-mobilization in 1992, and follow-up studies until 2005. The Welfare Alliance has been politically active from the start in 1998, and is still very active in 2012. They coordinate actions, demonstrations and conferences, and they cooperate with other initiatives to keep the fight against poverty alive. Since the 1980s poor people, social welfare clients and other marginal groups in Norway have been involved in mobilization, collective participation and collective action, a development that can be described as a social movement of people at the margins of Norwegian society.