Few issues were as particularly hot in the interwar period as the situation of the colonial empires and their evolution up to World War II. In line with the above, the debate that arose in the turbulent years between the wars on the limits of the colonialist imperialism of the European powers of the time, in the hand of a militant anti-colonialism, is worthy of study and assessment, as is done in this contribution. However, as we know, and as this chapter addresses and explains, beyond some processes of independence of countries subjected to colonialism, the decolonization process took on its own nature after World War II, being a theme of that historical process initiated with determination at the end of the war. In addition to the above, the aim is to verify, in the heat of history, whether the anti-colonial postulates were inspired by the Europeanism that also emerged in the troubled interwar years in the heat of the Pan-European movement.