The book Decipherment of Harappan Script is the result from an interest which the author developed in Harappan Archaeology since last 24 years during his slay in Institute of Archaeology London and later on in National Museum New Delhi where he was holding charge of Harappan material. Proto Dravidian and earliest Aryan were present in Harappan population. The author concluded Harappan script was Proto Brahmi and their languages were Proto-Dravidian Brahui and Laukik Sanskrit. The more positive chapter is identification of Harappan script sign. A unique contribution of the author is identification of Inscribed double headed terracotta Siva from Kalibangan. Which has three sign in proto-Brahmi script and author read these sign as Sivam.