This book examines the most significant factors accounting for the decline of union density during the neoliberal period, focusing on the case of Mexico. Union density, which reflects the representation of labor unions in the employed labor force, is one of the main indicators of union strength. The relation of organized labor with the state and the political system are also considered. The analysis is framed within a structure concentrated on cyclical, structural and political-institutional factors linked to labor union performance. Over the last decades, the transformations brought about by neoliberalism and democratization reshaped many features of the domestic political and economic model in Mexico. Therefore, an examination of these developments regarding the repercussions of the factors linked to union density decline is crucial.