This special issue shows how scholars in and from Central/Eastern/Southeastern Europe actively contributed to new social scientific concepts and systems, constructing a global imaginary in which to position themselves following the collapse of the continental European empires. The seven articles present under-explored intellectual biographies in the fields of economics, statistics, sociology, social medicine and psychiatry. In bringing to light the personal dimensions of scientific exchange and innovation, they show how transnational intellectual entanglements worked in practice between Warsaw and Paris, Kraków and New York, Polesie and Jamaica or Belgrade and Conakry.