Why do some rebel groups undertake costly, burdensome governing projects that undermine their legitimacy, and even trigger resistance and violence that could put their own combatants at risk, while other rebel groups do not? The introductory chapter uses the contemporary cases of three rebel groups’ control of the city Raqqa in Syria to illustrate the empirical puzzle that motivates the book. The chapter then outlines existing works related to rebel governance and details why these approaches cannot explain rebel governance in Raqqa. Specifically, research generally assumes that rebel governance is popular and desirable in ways that confer material and organizational benefits to rebel groups. This chapter then puts forth an alternative conceptualization of rebel governance as varied in terms of its costs and benefits such that rebel leaders make decisions about whether to introduce more or less burdensome governance institutions during war. The chapter then outlines the central argument of the text: that rebel groups’ goals determine their governance strategy. It then describes how the book empirically tests this argument before concluding with a discussion of the importance of the topic.