While aiming to define territorial control by armed groups in international law, this thesis establishes the impact of such control on their obligations under humanitarian law and human rights. First, it explains “territory” and its “control” in international law, and establishes the basis of applying international law to armed groups; second, it defines territorial control in humanitarian law according to six conceptions, advancing effective control based on analogy with occupation law; finally, it explains territorial control in human rights to include two conceptions, supporting functional control, while affirming obligations before control. Conclusively, though territorial control comprises varied meanings, movement towards a flexible definition is evident.