Multilateralism was strongly promoted during the Cold War by those who felt the unilateral use of American power was both illegitimate and dangerous. Now that the United States is in an isolationist phase and earlier obstacles to multilateral cooperation have been lifted, it suddenly finds it has the opposite problem: it wants to intervene everywhere with high moral purpose but has been bequeathed an instrument vastly too weak to achieve its ends. Enforcing Restraint thoughtfully reviews recent collective interventions in the former Yugoslavia, Iraq, Liberia, Haiti, Somalia and Cambodia, only the last of which could in any way be described as a success. The authors ponder questions such as the conditions under which collective intervention is legitimate and how existing mechanisms might be made more effective. As in the Brookings book above, one wonders whether purely multilateral intervention, without a strong component of American leadership, can ever be effective in the difficult cases where it really matters. Were ultilateralism to become an excuse for inaction on the part of national governments, it may do more harm than good.