This chapter examines settlement practice on detention in light of international humanitarian law and human rights law. Section 2 identifies the international legal frameworks that regulate detention, drawing the necessary distinctions between peacetime and armed conflict, and between international and non-international armed conflict, which frame questions on relevant applicable law. Section 3 then examines the specific legal norms relating to prisoners of war and civilian detainees within international armed conflict and their interaction with settlement practice; while Section 4 does the same in relation to legal norms regulating detention in non-international armed conflicts. In the context of peace agreements, the focus is on two interconnected issues which extend into a post bellum phase, as important subject matter for settlement practice: release and repatriation; and transitional justice. By way of conclusion, Section 5 considers whether settlement provisions on detainees reflect a common practice that develops international legal standards.