The author tests a set of hypotheses about the conditions under which
major powers intervene with military support for states that are threa
tened in a crisis. The hypotheses are derived from a general theoretic
al approach that integrates a realist framework with recent works that
focus on the domestic political determinants of foreign policy. Seven
of the eight hypotheses tested are supported by the results of legit
analysis on major power interventions in 272 international crises from
1918 to 1988. The broad theoretical implication is that scholars draw
ing on realist approaches to studying international politics should th
ink rigorously about the role of domestic politics in foreign policy d
ecisions.