There appear to be two seemingly contradictory images of economic change in the Islamic World and mixed evidence on whether Islamic societies have been open or conservative against modern ideas, technological advancements, and legal developments. Whereas a conservative attitude has been dominant in some societies and time periods, Muslims were at the forefront of scientific, technological, and legal developments in others. Rather than rely on ad hoc assumptions about the attitudes and characteristics of societies or the inherent qualities of new developments, this paper explains attitudes towards change by studying the political economy of the relationship between the rulers and the legal community. I extend recent theories of endogenous institutional change to develop a framework based on how rulers and legal community reacted to new developments immediately and how their strategic interaction unleashed an endogenous process toward change in the long run. Using this framework, I identify conditions under which new ideas, technologies, and legal developments have resulted in immediate change in Islamic societies. I also examine the process of change in the long run, whether and how immediate outcomes could be sustained over time as strategic interaction continued repeatedly.