Nationalism is an explosive topic at any time, but it is peculiarly explosive at this moment when the restraints of war have been lifted, when peace settlements are in prospect, and when national movements everywhere are again in full flower. The purpose of this paper is to examine the nature of nationalism in as uncontroversial and non-political a manner as the subject itself allows, and to compare its development in Southeast Asia with similar movements in other parts of the world. What is involved is an objective sociological investigation, and not an effort to arrive at value judgments which would answer such questions as whether this or that nationalist movement is good or evil or whether particular nationalist demands should be granted or opposed.