"Democracy and Interest Groups" assesses the contribution that interest groups make to the democratic involvement of citizens and the generation of social capital. It examines how interest groups are formed and how they maintain themselves - focussing specifically on the supply-side dimension of group membership that is how groups generate and stimulate citizen involvement. The authors draw on new surveys of groups and group members and, more unusually, with non-participants. It also makes use of in-depth interviews with campaign group leaders and organizers.