In this paper, we review the central claim of a growing literature: that is, that democratic
states rarely, if ever, wage war against and are very unlikely to engage in militarized disputes
with other democratic states. We ﬁrst examine the analytic foundations of this claim. We
conclude that they are tenuous. Next, we examine the evidence.
We ﬁnd that no statistically signiﬁcant relationship exists between regime type and the
probability of war before World War I. We also find that the probability of disputes short of war
is signiﬁcantly higher for democratic-democratic pairs than for other pairs of states in the pre-
1914 period. In both cases, our analysis shows that the hypothesized relationship prevails only
after World War H.
Because of the Cold War that ensued after 1945, our results suggest that the relationship
we observe between democracy and conflict is the product of common interests rather than of
common polities. An analysis of the relationship between regime type and the probability of
alliance formation lends support to this interpretation.