Founded in 1924 in the service of the League of Nations and the International Labour Organization (the world's first international organizations), it is the oldest international school in the world, and the largest one with 'international' in its name. It was the result of a partnership between parents (Arthur Sweetser and Ludwik Rajchman) and educators from the Institut Jean-Jacques Rousseau (Adolphe Ferrière and Paul Meyhoffer). In the mid-1960s, a group of teachers from Ecolint (La Grande Boissière campus) created the International Schools Examinations Syndicate (ISES), which later became the International Baccalaureate Organization (IBO) and then the International Baccalaureate (IB). Since its inception, the school's mission was conceived as educating for peace and the inculcation of humanitarian values such as inclusiveness, respect and inter-cultural understanding. It describes itself in its website as "resolutely not-for-profit; mankind is the only beneficiary of our work, not corporate shareholders or private equity firms." In 2017, it was labelled by ITN as "the most diverse school on the planet."