The introduction of a universal, egalitarian social security system was promoted by the USSR in all countries within its sphere of influence during the communist period. However, despite this rather uniform external pressure, communist countries followed different social policy routes in terms of timing and design. Bulgaria was one of the first Eastern European countries to introduce a uniform pension system within a short period of time. In this article, we argue that besides communist ideology and pressure from the USSR, pre-communist social policy legacies, national constellation of influential actors, and country-specific socioeconomic conditions during the communist era are crucial when explaining the concrete design and timing of pension reforms in communist states. Using the method of process tracing and based on archival and document research, we shed light on the two most important pension reforms targeting the rural population in communist Bulgaria. We show that the political and ideological developments in the Soviet Union in the 1960s and 1970s in combination with the demographic and economic problems of Bulgarian agriculture can explain the early establishment of a unified pension insurance system in Bulgaria.