The basic hypothesis that is examined posits a relationship between the magnitude of alliance commitment and war in the international system. We begin by establishing a theoretical connection between alliance commitment and war. A discussion follows of methodological considerations relevant to the empirical examination of the basic hypothesis. We specify several alternative forms of the relationship between alliance commitment and war and empirically evaluate them. Variations of the regression model are used to examine annual data on the number of defense alliance commitments and interstate war dyads per nation in the international system between 1816 and 1965. No impressive statistical relationship between the variables is located once the underlying statistical assumptions are taken into account, and it is argued that the basic hypothesis should be tentatively rejected. We close with suggestions for future research.