The dissertation traces the efforts of the Iraqi opposition to Saddam Hussein to influence United States foreign policy against Ba’thist Iraq between 1990-2003. Specifically, I examine the role of the Iraqi National Congress—an Iraqi opposition group led by the exiles Ahmad Chalabi and Kanan Makiya—to enlist domestic foreign policy elites to make regime change in Iraq the official foreign policy agenda of the United States. The dissertation draws on archival records from the Iraqi opposition and interviews with the architects of American foreign policy on Iraq. In emphasizing the non-domestic sources of American foreign policy on Iraq, I challenge and revise explanations for the causes of the 2003 war in Iraq which tend to focus on Saddam Hussein’s security threat to the United States or policymakers’ reactions to and compensation for declining American hegemony. I link the Iraqi opposition’s lobbying for policies against Saddam Hussein to a broader set of cases in which diaspora lobbies, governments-in-exile, and other transborder activists lobby host states for foreign policies against their home regimes. Drawing on the tools of political and cultural sociology and science and technology studies, I theorize the structural characteristics of the field of foreign policy, emphasizing elite control over foreign policy. I argue that a confluence of overlapping elite networks, epistemic authority, and cultural fluency positioned the Iraqi exiles in the INC to interfere with CIA efforts to covertly remove Saddam Hussein from power, to coauthor with neoconservative policymakers the Iraq Liberation Act of 1998, and to transmit an aggressive policy of de-ba’thification to the Department of Defense shortly before the invasion of Iraq in 2003. The dissertation makes contributions to the historical sociology of foreign policy, debates about agency and social change, and how we think about transnational activism and state power.