International trade agreements have often been criticized for limited attention to the rights of workers. The North American Agreement on Labor Cooperation (NAALC), a side agreement to the North American Free Trade Agreement (NAFTA), stands out for linking labor rights provisions to a U.S. trade agreement. Kevin J. Middlebrook provides a comprehensive and systematic examination of the NAALC, assessing its efficacy in protecting workers' rights over the entire period it was in effect and demonstrating its broader significance for the role of trade and labor standards in U.S. foreign policy. Placing the NAALC in comparative context, Middlebrook considers various ways of promoting workers' rights and how other U.S. international trade agreements have influenced labor rights abroad. He investigates the origins of the agreement; the political controversies among Canada, Mexico, and the United States over its scope; how the agreement operated in practice; and its longer-term policy legacies. Middlebrook emphasizes the tension between state sovereignty and the international promotion of labor rights in the negotiation and implementation of trade agreements, as well as how labor movements in one partner country can galvanize action in others. Drawing on interviews with high-level officials involved in the trade negotiations and previously unexamined primary sources, The International Defense of Workers is a groundbreaking analysis of the effects of U.S. trade agreements on labor rights.