Professor Prosterman practiced as an associate to the New York firm of Sullivan & Cromwell for six years before coming to the University of Washington in 1965. His research and teaching focus on legal issues of land reform, development, international, and property law fields, with a seminar in Legal Problems of Economic Development. He is also the director of the LL.M. Program in Law of Sustainable International Development. He has published Surviving to 3000: An Introduction to Lethal Conflict, (with Jeffrey Riedinger) Land Reform and Democratic Development, and (with Timothy Hanstad) Agrarian Reform and Grassroots Development. He has done field work in 27 developing countries. He received UW's coveted outstanding Public Service Award in 1990, and was appointed the University's first Corbally Professor in Public Service in Fall 1991.
He has twice been nominated for the Nobel Peace Prize. In April of 2003 he received the Gleitsman Foundation International Activist Award at Harvard University, honoring achievement in alleviating world poverty. He was selected for the award by a Board of Judges that included: former United Nations Secretary General Javier Perez de Cuellar and Nobel Peace Prize laureates Shimon Peres, Mairead Maguire, Archbishop Desmond M. Tutu and Adolfo Perez Esquivel. He and three other Gleitsman honorees share a $100,000 prize and received an original sculpture by artist May Lin, creator of the Vietnam War Memorial in Washington, D.C.