During this time Sen was also a frequent visitor to various other premiere Indian economic schools and centres of excellence like Jawaharlal Nehru University, Indian Statistical Institute, Centre for Development Studies, Gokhale Institute of Politics and Economics and Centre for Studies in Social Sciences. He was a companion of distinguished economists like Manmohan Singh (Ex-Prime Minister of India and a veteran economist responsible for liberalizing the Indian economy), K. N. Raj (Advisor to various Prime Ministers and a veteran economist who was the founder of Centre for Development Studies, Trivandrum, which is one of India's premier think tanks and schools) and Jagdish Bhagwati (who is known to be one of the greatest Indian economists in the field of International Trade and currently teaches at Columbia University). This is a period considered to be a Golden Period in the history of DSE. In 1971, he joined the London School of Economics as a Professor of Economics where he taught until 1977. From 1977 to 1988, he taught at the University of Oxford, where he was first a Professor of Economics and Fellow of Nuffield College, and then the Drummond Professor of Political Economy and a Fellow of All Souls College, Oxford from 1980.
Sen has been married three times. His first wife was Nabaneeta Dev Sen, an Indian writer and scholar, with whom he had two daughters: Antara, a journalist and publisher, and Nandana, a Bollywood actress. Their marriage broke up shortly after they moved to London in 1971. In 1978 Sen married Eva Colorni, an Italian economist, daughter of Eugenio Colorni and Ursula Hirschmann and niece of Albert O. Hirschman. The couple had two children, a daughter Indrani, who is a journalist in New York, and a son Kabir, a hip hop artist, MC, and music teacher at Shady Hill School. Eva died of cancer in 1985. In 1991, Sen married Emma Georgina Rothschild, who serves as the Jeremy and Jane Knowles Professor of History at Harvard University.