This article examines the century-long evolution of the Rashtriya Swayamsevak Sangh (RSS), from its founding in Nagpur in 1925 with mere 17 people to its centenary celebrations in 2025. Using contemporary reporting, organizational materials and established reference works, the paper traces RSS’s institutional development, ideological foundations in Hindutva, relationships within the Sangh Parivar (including links to political parties), its social and educational initiatives, as well as recurring controversies—most notably the 1948 ban after Mahatma Gandhi’s assassination. The analysis concludes with an assessment of the RSS’s contemporary position in Indian civil society and politics and identifies areas for future research.