How do citizens publicly express claims in totalitarian regimes? And how are the responses of authorities organized? I examine the participation and political control of Soviet citizens through letters to the editor during the late period of stagnation (1978-1982). Letters to the editor represent an underutilized source of political expression in the social sciences compared with opinion polls and focus groups. Letters offered Soviet citizens a tolerated way to participate in the political life of their communities. At the same time, Soviet authority responded to critical claims to legitimate their authority. I will present the reasons why citizens wrote letters, the common conventions they used to make claims on authority and how the responses of authority were organized.