The invasion of Grenada in October 1983 can be seen both as multilateral security's most striking recent success and as its most striking recent failure. The Organization of Eastern Caribbean States (OECS) authorized with extraordinary decisiveness and planned with extraordinary rapidity an invasion to rescue Grenadian citizens from the consequences of a coup that they found intolerable. At the same time, the invasion revealed the failure of the United Nations, regional organizations, subregional organizations, and alliances with powers outside the region to meet the ongoing needs of Caribbean ministates for national security and political independence. This chapter addresses two questions, concerning the roots and limits of escalation and the proper scope of international security, especially when escalation is endemic. It also deals with the wider reasons for the escalation beyond Grenada and the Eastern Caribbean of the conflict that began with the 1979 NJM "revolution" and culminated with the coup and the invasion.