In post-conflict settings where state and non-state legal orders coexist within the same territory, what factors determine individual preferences among alternative providers of justice and order? Are some people more prone to favor legal pluralism versus believing in the legitimacy of a single legal system for all cases? Or does it depend on the type of crime committed? Through a survey experiment conducted in the Iraqi city of Mosul, where the population has long been exposed to three alternative justice systems–state, tribal, and Islamic–we explore the relationship between state legitimacy and support for non-state legal authorities. The experiment helps us to parse out who is most likely to prefer legal pluralism–the application of different types of laws to different types of situations–in contrast to others who believe in the legitimacy of a single legal system to decide all cases that come before the law. We also expect, among other hypotheses, that Iraqis who stayed in Mosul after the Islamic State (IS) arrived in June 2014 (“stayers”) are more likely to prefer non-state legal authorities, whether tribal or Islamic, over state legal authorities in comparison with those who fled to government–controlled areas (“leavers”). Whether the data support or disconfirm these hypotheses, the results will have important implications for efforts by governments to establish legitimacy in areas where their sovereignty has been challenged by non-state actors.