Abstract: Since the latter years of the Cold War, strong democratic revolutionary movements seeking the overthrow of authoritarian regimes have arisen in many countries. Such movements have succeeded in some countries, including the Philippines (1986), South Korea (1988), the countries of Eastern Europe (1989), Russia (1991), and Serbia (2000). On the other hand, strong democratic movements which rose up in some countries were crushed before they could take power in China (1989), Burma/Mayanmar (1990), and Algeria (1992). Strong movements seeking the ouster of incumbent authoritarian regimes and their replacement by democratic government rose up in each of these cases. What, then, accounts for the success of democratic revolution in some of these cases and its failure in others? This paper will examine this question first through an examination of some of the theoretical literature on revolution, and then through a comparison of three cases of successful democratic revolution (the Philippines, Russia, and Serbia) with three cases of failed democratic revolution (China, Burma/Myanmar, and Algeria). Certain theorists, including Crane Brinton and Timothy Wickham-Crowley, have argued that the key factor in deciding whether or not non-democratic revolution succeeds or fails is the role of the armed forces. If the armed forces protect the ancien regime, then the revolutionary opposition is unable to seize power. If, however, the armed forces do not protect the ancien regime, then the revolutionaries usually do come to power. It will be argued here that just as in attempts at non-democratic revolution, the role played by the military is also the key factor in determining the outcome of democratic revolution. When the military is willing to use force to protect the ancien regime, democratic revolutionaries cannot prevail. It is only the refusal of the armed forces to do this that allows democratic revolutionaries to succeed. What, though, determines whether the armed forces of an authoritarian regime will use force to suppress a democratic revolutionary movement or not? Through a comparison of the cases mentioned above, I will argue here that the decision by the armed forces not to protect an authoritarian regime is not the result of a democratic conversion on the part of the military as a whole, but instead results from an overwhelming desire to prevent conflict within the military. Thus, if even a small number of key commanders defect to the democratic opposition, this can neutralize the armed forces as a whole even though most military leaders may be wary of, or even hostile to, democratization. But if these key defections to the democratic opposition do not occur and the military remains unified, it is able to crush the democratic revolutionaries easily......Paper presented at the annual meeting of the American Political Science Association, Philadelphia Marriott Hotel, Philadelphia, PA, Aug 27, 2003.