The purpose of this article is to emphasize the importance of the organizational blueprint of labor unions for welfare state outcomes. As a result of the tendency of scholars to view labor as a homogenous and disadvantaged class, the existing literature has paid little attention to this. Many scholars have simply taken labor union support for welfare state development for granted and consequently have focused only on labor union strength. This article argues, rather, that labor union support for welfare state development cannot be taken for granted. It shows that labor unions support or oppose welfare state development depending on their organizational blueprint. This new approach highlights the importance of the labor union movement's organizational structure, as opposed to its organizational strength, for welfare state outcomes. The article also explores how the organizational structure of the labor union movement shapes the stance of employer interest groups toward welfare state development. The empirical findings are based on a comparison of British and Dutch postwar old-age pension development