This article analyzes the role of human-rights ideas in the collapse of Communism. The demise of Communist rule in Eastern Europe and the Soviet Union was significantly influenced by the transnational diffusion of human-rights ideas. The analysis focuses on how human-rights norms were transmitted to Soviet dissidents and policymakers. The article also considers precisely how, and how much, these norms affected policy. The two primary causal mechanisms were the transmission of these ideas by a transnational Eastern European social movement for human rights, which expanded the roster of available political concepts and the terms of political legitimacy, and the mechanism of "rhetorical entrapment" whereby Soviet leaders became "trapped" or constrained to uphold their rhetorical commitment to the Helsinki Accords by the expanding discourse of human rights. Subsequently, Soviet leaders accepted human rights ideas for both substantive and instrumental reasons. Western power played some role, but the ideas themselves were salient, legitimate, and resonant for Soviet leaders seeking a new identity and destiny for the Soviet Union.