Despite the advances made by the international community to outlaw the resort to force by the United Nations Charter, armed conflicts both international and non-international are a fact of every day life. The civilian casualties from such conflicts have assumed catastrophic proportions. Little attention, however, has been paid by scholars to the treatment of noncombatants in armed conflict and the place in international law of the principle fundamental to the law of armed conflict: noncombatant immunity. This work aims to remedy this omission. The author analyses in detail the content of the customary and conventional rules that give effect to this principle, in both international and non-international armed conflict. The importance of such a study is highlighted by the recent Gulf conflict where so many of the States were not bound by the most recent treaty rules protecting noncombatants.