This thesis examines how workers at the bottom of global supply chains assert agency to improve their working conditions and how institutions constrain their ability to do so. Garment workers in Jordan, mostly migrants, face severe constraints on collective action given the legal restrictions on labor organizing, intensive cost pressures from global buyers, and the kafala system which ties migrant workers to a single employer and limits their ability to leave. Despite these constraints, my analysis of a novel dataset of 146 strikes from the 2010-2023 period shows that wildcat strikes led by migrant workers were mostly successful. However, I find that after 2016 strikes shifted from being offensive—seeking improvements—to defensive—aimed at protecting existing rights. Based on a review of sectoral collective bargaining agreements (CBAs), and 40 interviews with stakeholders including workers, union officials, factory managers, and policymakers, I argue that the primary cause was the growing alignment of interests between the sector’s single union and that of employers. This alignment allowed employers and the union to use the collective bargaining system, which was institutionalized as a result of the successful strikes in the early period, to constrain workers’ associational power over the last decade. While some signs of worker resistance and organizing capacity still remain, these are increasingly constrained by management practices and a union that prioritizes industry stability over advocacy on behalf of workers.