Advanced postindustrialization generates numerous challenges for the European social model. Central among these challenges is declining income, unstable employment, and inadequate training of semi- and unskilled workers. In this chapter, I assess the partisan basis of support for social policies that address the needs of these marginalized workers. I specifically consider the impacts of postindustrial cleavages among core constituencies of social democratic parties on the capacity of these parties to pursue inclusive social policies. I argue – and find support for in empirical analyses – that encompassing labor organization is the most important factor in strengthening the ability of left parties to build successful coalitions in support of outsider-friendly policies. I go beyond existing work on the topic by considering the full array of postindustrial cleavages facing left parties, by more fully elaborating why encompassing labor organization is crucial, and by considering a more complete set of measures of outsider policies than extant work. I compare my arguments and findings to important new work that stresses coalition building and partisan politics but minimizes the role of class organization