Over the past century, the Hindu right-wing group known as the Rashtriya Swayamsevak Sangh has transformed from a marginalized organization into a dominant force shaping India's political and social landscape. Prime Minister Narendra Modi, a lifelong member, has publicly acknowledged the group's influence, reflecting its ascent to mainstream power as it marks its 100th anniversary. The group has built a vast network that reaches into nearly every aspect of Indian society, from government and courts to media and education, mobilizing millions through local cells and affiliated organizations. While the Rashtriya Swayamsevak Sangh publicly promotes discipline and social service, its affiliates have been linked to rising religious tensions and violence against minorities, fueling deep divisions in the country. As the organization pushes its vision of a Hindu-first nation, its leaders navigate a complex balance between public inclusivity and hardline activism, ensuring its influence will persist well beyond the current political leadership.