The study of military effectiveness in political science has come a long way in a short period of time. When I started graduate school in the mid-1990s, most of the key works on the subject were written by historians and sociologists rather than political scientists. Beginning in the late 1990s, however, military effectiveness began to enter the mainstream of international security studies in political science. Scholars began to produce a series of works that detailed, inter alia, the martial shortcomings of dictatorships and Arab states, the battlefield virtues of democracies, the critical importance of the ‘modern system’ of force employment, and the link between civil-military relations and effective preparation for and conduct of hostilities. Lively debate continues on many of these subjects, particularly the relative effectiveness of different regime types and how civil-military relations influence adoption of the modern system. This debate has unfolded primarily in the context of conventional (interstate) war, but a related literature on effectiveness in counterinsurgency has been reinvigorated in the wake of U.S. occupations in Afghanistan and Iraq.