This paper seeks to explain the apparent paralysis that has affected efforts to address the very real immigration problems the United States faces. The answer appears to lie in the divergence between the politics and the economics of immigration that has prevented the Congress from adopting comprehensive reforms that would rationalize an immigration system riddled with contradictions and continuing tolerance for illegal migration. The paper begins with a historical overview of immigration policy decision-making processes in the United States. It then briefly presents current immigration policies and explains their successes and failures. This section also sets out the principal policy recommendations that have been under consideration to reform immigration. The paper then discusses three factors that help explain the difficulties in enacting comprehensive reform: 1) the coalitions that form around immigration policy, which often successfully coalesce over specific provisions in the law but break apart over others; 2) public ambivalence about immigration, particularly among those who see their own immigrant forebears through rose-colored glasses but are fearful that today’s immigrants will fail to adopt to American norms and values; and 3) practical impediments that make effective reform difficult to achieve. The final section discusses future prospects for immigration reform and presents recommendations for steps that may help achieve that end.