Focusing on communist Bulgaria (1960s–1989), this book shows how a marginal and ostensibly ‘neutral’ science enabled unexpected flows of knowledge, expertise, and practice between the East and the West. Situating Bulgaria within broader regional and international contexts, it highlights how gerontology’s peripheral position opened space for internationalisation, collaboration, and exchange during the Cold War. By tracing these entanglements, the study challenges binary narratives of East and West and offers a new perspective on the history of medicine, ageing, and socialist science. The history of gerontology suggests that the Iron Curtain was never as impenetrable as its name implies, but woven, porous, and unexpectedly permeable, allowing ideas and practices to slip through its threads. Drawing on institutional archives, oral histories, and personal collections, the book demonstrates how gerontology shaped representations of ageing, influenced policies toward the elderly, and afforded scientists a measure of autonomy under socialism.