In November 1945 Salem was reopened by Marina Ewald, a former staff member and confidante of Kurt Hahn. Salem was able to take up where it had left off in 1941 under the leadership of a series of heads of school - Prince Georg Wilhelm von Hannover, Axel Freiherr von dem Bussche, Horst Freiherr von Gersdorff and Hartwig Graf von Bernstorff - and consolidate its position in the German educational landscape. In 1950 the Altsalemer Vereinigung (ASV), the alumni association, was re-established.
In 1962, Kurt Hahn founded the first United World College, the UWC of the Atlantic. Staff members of that College, in turn, helped in 1968 to initiate the International Baccalaureate Programme (IB ) which incorporates a program of extracurricular pedagogy as envisioned by Kurt Hahn.
During Kurt Hahn's 80th birthday celebrations in June 1966 one of his first pupils and later pedagogical companions, Jocelin Winthrop-Young, suggested the founding of an international network among schools which follow Hahn's pedagogical philosophy. Named after a round barn within the round courtyard of Gordonstoun, it became known as the Round Square. This association of boarding schools all over the world laid an important foundation stone for Salem's internationality, which since the 1990s has found expression in the International Baccalaureate track, in its community of pupils and teachers from over 40 nations, and in the program of 1:1 pupil exchanges with over 50 partner schools on five continents.