The essays--prepared for a Massachusetts Institute of Technology faculty seminar--show how Hirschman's innovative ideas bear on the theory, policy, and practice of development in the 1990s. Hirschman, one of the great pioneers in the field of economic development, is now professor emeritus at the Institute for Advanced Study at Princeton. Paul Krugman, Lance Taylor, and Donald Schon begin by addressing the different approaches and assumptions of economic theorists in relation to modelling, learning, and development policy. Emma Rothschild, Lisa Peattie, and Bishwapryiya Sanyal examine some of the changing attitudes toward economic progress. Elliot Marseille, Judith Tendler, Sara Friedheim, Robert Picciotto, and Charles Sabel draw lessons from efforts to innovate or modify institutions, policies, programs, and projects. Except for Rothschild of King's College, Cambridge University, and Riccioto, the World Bank, these contributors are, or were, affiliated with MIT. The underlying themes that emerge all touch in one way or another on the ideas of development as a process of social learning. In a postscript, Albert 0. Hirschman reflects on the evolution of his ideas, his cognitive style, and his propensity for self-subversion. Two appendixes detail the candid seminar discussions and Hirschman's musings in response to particular chapters and questions raised by the participants.