Advanced postindustrialization generates numerous challenges for the European social model. Central among these challenges is the problem of addressing new risks associated with employment and skills 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 durable and electorally successful coalitions in support of outsider-friendly policies. I go beyond existing work on the topic by considering the full array of postindustrial cleavages and electoral challenges facing left parties, by more fully elaborating the logic of 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.