Following some preliminary remarks on the concept of secession and its status in international law, this chapter examines competing answers to two questions that any theory of state secession must address.First, what sort of actor enjoys a prima facie moral right to secede, and in virtue of what features or considerations does that actor do so?Second, on what particular territory is an actor with a right to secede permitted to exercise that right?It then evaluates arguments for and against several international legal norms that might be adopted to regulate unilateral secession, drawing on both moral theories of secession and empirically informed conjectures regarding the incentives those norms might create for various international and domestic actors.