Kothari was the only son of his father, a Jain trader. His mother died early in life.
Career
Kothari started his career as a lecturer at Maharaja Sayajirao University of Baroda. While working here he first received recognition in 1961, when his essays series, "Form and Substance in Indian Politics" were published in the Economic and Political Weekly over six issues. He had also started writing for Seminar, the journal published by Romesh Thapar. Thereafter he was invited by Professor Shyama Charan Dube to become the Assistant Director of the National Institute of Community Development, Mussoorie. In 1963, he moved to Delhi, where using a personal grant of Rs. 70,000 given by Professor Richard L. Park, head of Asia Foundation’s India chapter, he started the Centre for the Study of Developing Societies, in the premises of the Indian Adult Education Association at Indraprastha Estate, Delhi, before moving to its present location in Civil Lines, Delhi. Here working along with Ashis Nandy, D.L. Sheth, Ramashray Roy, Bashiruddin Ahmed and others, pioneering works in social sciences were published over next two decades. In 1970 he published Politics in India, which first theorized Indian National Congress as a system rather than a party. Thereafter he published noted works like Caste in Indian Politics and Footsteps into the Future. During the early 1970s, he was associated with Congress-leader Indira Gandhi, and negotiated with the Congress-led central government for Navnirman movement, a socio-political movement of 1974 against corruption in Gujarat, which ultimately led to the dissolution of the state government. However, with the entry of Sanjay Gandhi, he distanced himself from Congress, and came close to Jaya Prakash Narayan and the Janata Party instead. After the Emergency of 1975, he moved away from political parties, and started his career as an activist. This phase culminated with the foundation of Lokayan - Dialogue of the People in 1980, a forum for interaction between activists, thinkers and intellectuals to talked about positive changes in the fields of religion, agriculture, health, politics, and education. He soon became associated with Citizens for Democracy, and People's Union for Civil Liberties, a human rights body established in 1976, where he remained General Secretary from 1982 to 1984, and subsequently its President. He served as the chairman of Indian Council of Social Science Research and remained a member of the Planning Commission. Besides scholarly articles he also wrote newspaper columns, and in 2002 published his memoirs titled, Memoirs: Uneasy is the Life of the Mind. CSDS where he was an honorary fellow, in 2004 established The Rajni Kothari Chair in Democracy in his honour, funded by Ford Foundation and the Sir Ratan Tata Trust. On 27 November 2012, CSDS celebrated its 50th anniversary, presided over by Kothari.
Personal life
He married in 1947, and his wife Hansa died in 1999. In his final years, his eldest son Smitu died in 2009. Smitu, trained in physics, communications and sociology, was involved in ecological, cultural and human rights issues. He had been a visiting professor at Cornell and Princeton Universities.Rajni Kothari had two other sons, Miloon and Ashish, and two grandchildren, Emma and Gyan.