This dissertation explores how workers and their organizations in the United States utilize the strike, labor’s most potent tool for asserting power. Drawing on 108 interviews and an original, comprehensive database of strike activity, this dissertation problematizes conventional perspectives on strikes and strike effectiveness that narrowly analyze work stoppages during the course of institutionalized bargaining relationships. Rather than occurring solely as the product of failed contract negotiations between unionized workers and firms, strikes emerge in a variety of institutional contexts and assume multiple forms. Based on qualitative interviews and fieldwork, I develop a typology of strikes that reflect their multidimensionality and unpackage the multiple ways that workers conceptualize strike outcomes and effectiveness. Unlike much of the existing literature on labor revitalization and power resource theory that focuses almost exclusively on labor’s strategy and agency, this research emphasizes the importance of examining power relationally by also studying employer behavior. I elaborate a theoretical framework that incorporates employer power resources and strategic capabilities into an analysis of strike outcomes, finding that employers fundamentally shape the deployment and effectiveness of labor’s strategies and resources.