This is a voluminous philosophical treatise in Sanskrit which seeks to defend the Nyaya Vaisesika conception of self by critically examining and refuting the Buddhist doctrine of Universal momentariness, unreality of the objective world and so on that are directly or indirectly opposed to the reality of self. As a work of unrelenting and sustained polemics, Atmatattvaviveka ha no parallel in the philosophical literature of India or the West. Udayanacarya the author of the work was a giant of a scholar who syncretised the Nyaya and Vaisesika schools and put them on a firm logical foundation by writing both destructive and constructive works on the philosophy of the schools. The controversy between Nyaya Vaisesika and Buddhism dates back to the 2nd century AD when Vatsysysna wrote his Bhasya commentary on the Nyayasutras and criticized therein the views of Nagarjuna, Vasubandhu etc. the great Madhyamika Buddhists. The process of criticism and counter-criticism of each other views in the Nyaya Vaisesika and the Buddhist schools continued unabated after the advent of Vatsyayana's Bhasya for about a thousand years. Only when they appeared on the scene did the age-old controversy between the two hostile philosophical camps came to an abrupt end. No Buddhist scholar ever dared to challenge the criticism of the Buddhist views contained in the Atmatattvaviveka. Many eminent scholars have commented upon this work. In preparing this translation-sum-explanation of the work all-important commentaries of the work available today have been utilized. Philosophical issues of current interest are also incidentally discussed in the work.