This dissertation is a study of African Americans and U.S. foreign policy toward Africa in the post-civil rights era. It adds to the literature on African Americans in international affairs by exploring the ways that the liberation movements in Southern Africa became a central focus among Black leaders in different ideological camps. It also highlights Congressional politics, mass mobilization, and institution building as strategies employed by African American activists to challenge U.S. political and economic policies toward Southern Africa. Chronicling the rise and fall of these approaches, this study also gives significant attention to the founding of the foreign policy lobby TransAfrica in 1977. Moreover, it highlights how TransAfrica became the principal intermediary for African American interests in U.S. foreign policy, as exemplified by its rise to the forefront of the U.S. based anti-apartheid movement activities. Drawing upon the fields of African American politics, African American history, and international relations, and theories of transnationalism and diaspora, I provide an alternative conceptual framework for the intersection of race and foreign policy. To these ends, this project offers the concept "adversarial diplomacy" to characterize the activities of non-state actors that circumvent the diplomatic functions traditionally reserved by the state. Focusing on the international political activism of African Americans, this study highlights Congressional politics, intellectual politics, mass mobilization, and institution building as dominant approaches to adversarial diplomacy.