There is a widespread consensus in the literature about the positive effects of having allies in congress for the legislative consequences of social movements. However, social scientists know little about the dynamics associated with this kind of interaction. Scholars have attempted to unravel the nature and consequences of these alliances, but they remain a black box because of the use of theoretical proxies. A growing body of literature realizes the limitations of this approach and has started to advocate for a more focused and detailed analysis that pays attention to the interactions and perceptions of the activists and legislators involved in an alliance. I contribute to this area of inquiry by examining the interplay of activists and their allies in congress following a grounded approach, using the case of the Chilean environmental, LGBT and labor movements. By interviewing activists and their allies in congress, I could obtain detailed data on the perceptions, motivations, and extent of their interactions.

As part of this dissertation, I develop a nuanced theoretical understanding of the motivations and exchange patterns involved in the alliance activists forge with members of congress. Then, I analyze different strategies social movement organizations can use to establish that kind of tie with a legislator. Finally, I assess the consequences of having an ally in congress for the achievement of activists’ demands. I find that an alliance between activists and legislators is a complex kind of social relation motivated by different rationales of action that shape the contours of their interaction and that having these allies has a positive effect for the leverage of activists throughout the lawmaking process. These findings contribute to the theoretical and methodological analysis of the alliance between activists and legislators, opening a debate about how their interaction and cooperation brings about policy and social change.