The experiences of World War II resulted in radical changes in the Australian immigration policy. The mass character of immigration and, most of all, its diverse national composition lead to deep social and cultural changes. Within two decades, not without a struggle, the relatively ethnically homogenous, “truly British” society of the Commonwealth of Australia which was formerly separated from the world through the “tyranny of distance”, turned into a multiethnic society characterised by great social and cultural diversity. This necessitated adjustments in the state policy, which evolved from assimilationist to multicultural, and changes in social attitudes and the Australian national identity. This article takes a historical perspective and aims at outlining the sources, assumptions and actual course of postwar immigration and its major social and cultural implications. It presents the period until the mid 1970s, i.e. until the Labour government led by Gough Whitlam, who initiated the politics of multiculturalism, was is office.