The diaries of Nikolai P. Kamanin, a well-placed official in the early Soviet space program in charge of cosmonaut selection and chaperoning, have been an important source for historians since their publication in the 1990s. This article reevaluates the diary entries from 1961 to 1965, using the framework of gossip. The diaries’ salacious tales of infidelity, drinking, and other violations of communist morality provide cultural historians with as much insightful material as the parallel technological entries have done for historians of science and space engineering. The cosmonaut gossip that Kamanin records comprised a mix of knowledge production and moralizing that built and reinforced his self-fashioning among the Soviet elite. Furthermore, reading the diaries (a private text) through the lens of gossip (a public act) helps us see how socialist masculinity was forged in part through the specific hybridized private-public performances required of elite men.