The International Military Intervention (IMI) data set records events involving “the movement of regular troops or forces (airborne, seaborne, shelling, etc) of one country inside another, in the context of some political issue or dispute” (Pearson and Baumann, 1993, 1). Paramilitaries, government backed militias, private security forces, and other military units that are not part of the regular uniformed military of the state are excluded. Similarly, events must be purposeful, not accidental. Foreign military interventions are the result of conscious decisions by national leaders. Random or inadvertent border crossings are not recorded, nor are unintentional confrontations between fighter planes or naval ships. In all, 1114 cases meeting these criteria are cataloged for the years 1946 to 2005. Twenty-seven separate pieces of information are coded for each case in an attempt to capture multiple dimensions of the intervention. One result is that the IMI collection has considerable substantive breadth. Analysts can easily separate out and focus on the forms of intervention (supportive, hostile, humanitarian, territorial, etc) that are relevant to their research.