The 2010 US campaign and election was pivotal: the Republican takeover of the House, the advent of 'super PACs', and record-breaking sums spent on a midterm election. More than ever before, interest groups were able to mobilise new resources and new technologies in a shifting set of House and Senate races. This volume explores - in a series of lively case studies - a cross-section of groups, communities, and networks that vividly illustrates the 'unleashing' of interest group activity in the electoral process in response to Citizens United and other court cases and events.