In an era of widespread concern about a decline in political and civic activity (and party decline) Democracy and Interest Groups assesses the contribution groups make to the democratic involvement of citizens. It examines how interest groups are formed and how they maintain themselves - focussing specifically on the under-researched supply-side dimension of group membership: i.e. how groups generate and stimulate citizen involvement. The volume includes new surveys of, and in-depth interviews with, campaign group leaders and new survey data on the reasons members of environmental groups advance for their participation and almost uniquely survey data on the reasons potential members of environmental groups (i.e. citizens with strong pro-environmental attitudes that would suggest membership) advance for their nonparticipation.