The guest list included nearly 4,000 names -- there were members of of the outgoing Nehru Gandhi-dynasty, Afghanistan's Hamid Karzai and even Nawaz Sharif - the prime minister of arch rival Pakistan.
Narendra Modi's team broke with tradition, opting to hold the event outside the presidential palace to accommodate the huge audience.
Modi, the lower caste son a of a tea stall owner, arrived on time --- a point local media reported was highly unusual for an Indian leader.
Amid cheers, Modi took his oath and then sat for the signing ceremony.
While his critics have accused him of harboring Hindu supremacist views, Modi's team in recent days has taken steps to appear inclusive --- most notably inviting Muslim neighbor Pakistan's Sharif to attend.
The 90-minute ceremony ended with Modi posing with party officials followed by a group photo with visiting heads of state --- perhaps a nod to the larger role India hopes to play on the world stage.
