The Indian National Congress (Organisation) was a political party in India formed when Indira Gandhi (then the Congress president) broke away from the party leadership. As Indira had control over the state machinery, her faction was recognized as the "real" INC by the Election Commission of India, so the rump INC became known as the INC(O), or informally the "Old Congress". The Tamil Nadu kingmaker Kamaraj became the leader of the INC(O).

The split can in some ways be seen as a left-wing/right-wing division. Indira wanted to use a populist agenda in order to mobilize popular support for the party. The regional party elites, who formed the INC(O), stood for a more right-wing agenda, and distrusted Soviet help.

At the 1971 general election, the INC(O) won about 10% of the vote and 16 Lok Sabha seats, against 44% of the vote and 352 seats for Indira's Congress. In 1977, their vote share was almost halved and they lost 3 seats. Later the same year, INC(O) merged with the much larger Bharatiya Lok Dal and other parties to form the Janata Party as a more united opposition to Indira's rule.