This article explores the complex interactions between diplomacy and human migration as a fundamental component of U.S.-Cuban relations in the late 1970s. It assesses U.S. and Cuban leaders’ intentions in pursuing bilateral normalization, as well as their responses to the competing opinions of the Cuban-American community in Miami. The article also examines the opening of the secret U.S.-Cuban talks, the growing mistrust and suspicion among Washington and Havana, and the breakdown of communications prior to the Mariel boatlift of 1980. Drawing on U.S., Cuban, and Cuban-American resources, the article shows that the complex triangular relationship linking Washington, Havana, and Miami was crucial in the short-lived U.S.-Cuban dialogue. The article demonstrates that miscommunication and disagreements over Cuban migration were just as important as the U.S.-Cuban clash over the Cold War in Africa in undermining the spirit of that dialogue.