Greif, Avner, Institutions and the Path to the Modern Economy: Lessons from Medieval Trade. Cambridge University Press, 2008, pp. 452, Price £19.99. In a comparative study of the late medieval European and Muslim worlds, Greif analyzes the effect of institutions—especially those that facilitated impersonal exchange, such as trade—on the performance of modern economies. His argument rests on the premise that past institutions have an effect on consequent ones, and he contributes the disparity in performance of the Muslim and European economies to their distinct institutional trajectories. The book comprises several parts. It defines institutions in great detail; provides a comparative account of institutions in the medieval European and Muslim worlds; and applies a theoretical, analytical, and empirical framework—particularly game theory—to studying institutions.