This thesis examines governance in Syria’s Idlib governorate between 2011 and 2021, during the ongoing civil war. It shows civilians’ importance as frequently autonomous governance providers in rebel-controlled areas and introduces the concept of ‘governance under insurgency’, encompassing governance provided by rebels as well as alternative governance providers (AGPs) in rebel-controlled areas. Bringing together insights from the literatures on rebel governance and governance in areas of limited statehood, the thesis contributes to theorybuilding on governance in rebel-controlled areas by establishing a typology and analytical framework to explain variation in relations between rebels and AGPs. The typology distinguishes different degrees of AGP autonomy from rebels. It also distinguishes between governance forms making life predictable for civilians and those that do not. The typology encompasses five types of governance under insurgency (non-rebel, joint, contested, rebelimposed or suppressed governance). The configuration of six explanatory conditions explains variation, including rebels’ perception of AGPs as competitors, rebels’ degree of military control, rebels’ and AGPs’ governance capacity, AGPs’ ability to cooperate with rebels and rebels’ perception of the population as (non-)constituents. The thesis is based on primary evidence collected during three rounds of fieldwork in Turkey and Jordan and remotely, primarily but not exclusively interviews. It analyses justice and law enforcement, healthcare, and bread provision in Greater Idlib. Comparing governance outcomes in these sectors over time shows that variation in the conjunction of the explanatory conditions explains governance outcomes and their evolution. It also demonstrates that AGPs can have significant agency in shaping governance outcomes, even against rebel preferences, and the importance of looking beyond governance by or on behalf of rebels to capture the full scope of governance provision in contexts of insurgency. Additional probing cases test the analytical framework, examining governance in rebel-controlled Darʿa and northeast Syria, establishing the framework’s relevance beyond Idlib.