Abstract
This article investigates why, in two different political and institutional contexts, leftist governing parties became agents of empowered inclusion, boosting the capacity of subordinate social actors to shape the agenda of politics and allowing them to push social policy in an inclusionary direction. To explain how and why this happened, it highlights the ambiguous nature of party-society linkages. While societal ties are necessary for sustained significant progress in social and political inclusion, they can also block the later consolidation of achievements. This happens as some groups, once included, block further inclusion. We build our theoretical argument about the two-sided nature of party-society linkages using comparative evidence from Bolivia and Uruguay-two countries where progress toward empowered inclusion has been especially notable in the past two decades. The article contributes to existing scholarship on social and political inclusion by calling for greater attention to the critical but, at times, ambiguous role that the social bases of parties play.