Two time winner of the Nikkei Prize (in 1984 and 1988), the works of acclaimed welfare economist, as well as social choice and industrial organization theorist, Kotaro Suzumura are here collected for the first time. In 2004, he was conferred the Medal with Purple Ribbon for his contributions to theoretical economics. In 2006, he received the Japan Academy Award for his contributions to welfare economics and social choice theory. Kotaro Suzumura is Professor of Public Economics at the Institute of Economic Research, Hitotsubashi University since 1984, Director of the Competition Policy Research Center within Fair Trade Commission of Japan since 2003, and, since 2006 Vice President of the Science Council of Japan.