Sen grew up in New Delhi, attending Sardar Patel Vidyalaya and then St Stephen's College for a Physics Honours degree. . He has a PhD in Economics from the University of Cambridge in 1981 where he was a member of Trinity Hall and wrote a thesis titled "The agrarian constraint to economic development: the case of India" under supervision of Prof. J. A. Rowthorn
He has been the Chairman of a number of official Commissions, including the High Level Committee on Long Term Grain Policy, Commission for Agricultural Costs and Prices, the Tenth Plan Subgroup on Agricultural Economics and Rural Development.
He has been a Member of the State Planning Boards of West Bengal and Tripura, PM's Taskforce on Agricultural Economics and Rural Development, and the Expert Committee on Rural Credit.
Sen has also been Adviser/Consultant with International organisations, such as the United Nations Development Programme, New York; International Labour Organization, Geneva; Food and Agricultural Organisation of the United Nations, Rome; OECD Development Centre, Paris; the UN University World Institute of Development Research, Helsinki; International Fund for Agricultural Development, Rome; Asian Development Bank, Manila.
Sen has authored /Co-authored more than 30 papers.