Diverse Interest Group Coalitions and Social Welfare Policy in the United States

American legislators are unlikely representatives for the needs of the poor. As reelection-seekers, legislators have few incentives to devote scarce resources to constituents who can neither promise electoral rewards nor threaten electoral punishment. Yet organizational advocates for the poor are active in lobbying legislators and testifying at hearings. And despite the fact that they have few resources, advocates sometimes emerge from legislative battles victorious. Why does this occur? How and under what conditions do advocates gain influence in legislative settings?;In this dissertation, I develop a theory of diverse coalition formation by interest groups to explain one way that organizational advocates for the poor achieve influence in legislative settings. Building on literature on lobbying, information, and influence in Congress, I theorize that although advocates have limited funding and small membership bases, they can gain influence by building diverse coalitions with other interest groups. In building diverse coalitions, advocates can provide legislators with different types of informational resources, as well as a wider range of the same type of informational resource. Because coalition building is costly, it can convince legislators that the information being provided by the interest groups is credible. Diverse coalitions can therefore help advocates influence legislative outcomes.;I use a multi-method approach to derive the conditions of coalition building and influence and to test the theory's implications. My formal-theoretic model predicts that advocates will build diverse coalitions when issues are salient to advocates and partners, conflict between opposing interest groups is high, and opposition to social welfare programs in the legislature is high. My empirical analysis focuses on interest group activity and national and state policy decisions preceding and following the passage of the federal welfare reform of 1996. Using a quantitative cross-state analysis of welfare policy decisions, and qualitative analyses of lobbying and policy decisions at the national level and in 15 states, I find that many advocates engaged in diverse coalition building as a strategy of influence during welfare reform. Most coalitions were informal rather than formal, and were sometimes---though not always---associated with legislative influence.