Karat (56), who took over from the Marxist veteran Harkishan Singh Surjeet on April 11, 2005, joined the party in 1970, after returning to India with a post-graduate degree in Politics from the University of Edinburgh. (His suspension was later revoked due to good behaviour). He worked as an aide to Mr A K Gopalan, leader of the CPI(M) Parliamentary Group, for two years. He was involved with student politics and went on to become the Jawaharlal Nehru University Student's Union President from 1972-1973 and the first President of the Students Federation of India from 1974-1979.
He worked underground during the Emergency in 1975-76 and was arrested twice.
Karat's ascent in the party began in 1982 when he became the CPI(M) Delhi State Committee Secretary. He was elected to the CPI(M) Central Committee in 1985.
There was no looking back for Karat after he became a member of the Politbureau, the highest decision-making body of the party, in 1992.
The party's top post of General Secretary beckoned him in 2005, ushering in a generation change in the CPI(M).
Karat, whose wife Brinda Karat was also a member of the CPI(M) Central Committee, had graduated from the Madras Christian College, where he won the medal for best outgoing student for all-round activities.
Karat was on the Editorial Board of 'The Marxist', the theoretical journal of the CPI(M), since 1992. Besides, he was the Managing Director of LeftWord Books, a leading Left wing publishing house.
He had authored 'Language, Nationality and Politics in India' (1972) and edited 'A World to Win - Essays on the Communist Manifesto' (1999) and 'Across Time and Continents: A Tribute to Victor Kiernan' (2003).