This book traces the history of Hindu nationalism with a special focus on the Rashtriya Swayamsevak Sangh (RSS) as its prominent flag bearer. Through an in-depth study of archival sources and more recent documents, the author challenges the claim of Hindu nationalism as being primordial. He argues that in addition to being a modern construct, it laid the foundation of Hindu separatism or a two-nation theory which was later adopted by Muslim separatists like Mohammed Ali Jinnah. This book describes the growth of Hindu nationalism and its appearance as Hindutva which glorifies Casteism, Racism and totalitarianism. This work also investigates how the book Hindutva authored by VD Savarkar (1923) and MS Golwalkar's We or Our Nationhood Defined (1939) continue to determine the discourse of Hindu nationalism. The author has spent more than three decades collecting and scrutinizing original RSS documents from different parts of the country, especially the ones relating to pre-Independence India. These documents are the foundation for the direction which RSS was destined to take as a sectarian Hindu separatist organization opposed to democratic, secular and egalitarian ideals.