As unions in most other industrialized democracies continue to decline, unions in Spain have been able to regain and maintain strength despite unfavorable institutional, political, and economic conditions. This book analyzes the trajectory of Spanish unions from the last decade of the Franco dictatorship until the early twenty-first century through a historical and institutional lens. Positioning Spanish unions and industrial relations within a comparative framework, this volume highlights the seeming anomalies of the Spanish case: rising affiliation rates in the 1990s when those of many other countries were declining; general strikes and weakening social pact during Socialist party governments; or a renewal of social pacts when a conservative party ascended to power. The Politics of Industrial Relationsmakes several major contributions. First, no other book offers a current comprehensive study of Spanish politics, unions, and industrial relations. Second, the book places unions in their political context, thus illuminating the puzzle of how leftist parties succeed in winning elections and unions continue to exert political influence when the previously strong ties between them have been cut. This speaks to the literature analyzing the links between leftist parties and unions, generally based on the assumption of a symbiotic relationship between the two as a precondition for mutual success. Finally, the book adds to the comparative industrial relations literature, challenging many commonly held assumptions about the fate of unions, the institutional preconditions that favor union resilience, and the effects of globalization on domestic economic actors. Comprehensive in its theoretical scope and empirical depth, the book presents Spain as an anomaly, and thus as a test case, for a multitude of theories developed in the political economy and industrial relations literatures.