This study establishes that the political, economic and military-technological changes that transform the international system also alter the way in which a state views its and others’ responsibilities and burdens for responding to international crises. It assesses the distribution of the costs of raising and supporting arms of service, the risks of deploying them overseas and using them in combat or peace operations, and the extent to which members have a responsibility for maintaining international order in the context of three instances of multinational military intervention: the Multinational Force deployment in Lebanon in 1982-83; the first Persian Gulf War in 1990-91; and the UN and NATO intervention in Bosnia-Herzegovina.