ENThis article explores the KGB’s use of undercover agents to forestall and investigate dissenting behaviour in the Lithuanian SSR during the 1950s and 1960s. Drawing primarily on declassified KGB documents from the Lithuanian Special Archive, it presents new details on the scope, methods, targets and results of agent work as the Soviet regime moved away from the mass repressions of the Stalin years, highlighting both change and continuity, as well as key successes and failings in this sphere.