This study presents a comparative approach to a universal theory of TENSE, ASPECT and MOOD, combining the methods of comparative and historical linguistics, fieldwork, text linguistics, and philology. The parts of the book discuss and describe (i) the concepts of TENSE, ASPECT and MOOD; (ii) the Tibetan system of RELATIVE TENSE and aspectual values, with main sections on Old and Classical Tibetan, "Lhasa" Tibetan, and East Tibetan (Amdo and Kham); and (iii) West Tibetan (Ladakhi, Purik, Balti); Part (iv) presents the comparative view.