This article contends that the relationship between the military and democracy is inherently problematic, even in advanced democracies, but more so in developing countries, including those where transitions to democracy have recently taken place. These transitions have usually been speeded by the fracturing of authoritarian regimes and their military and security structures (which are seldom completely monolithic). An analytical model illustrates the differing circumstances in which this fracturing produces democratization, rather than intensified repression, armed conflict or state collapse. The article goes on to argue that democracies will remain at risk so long as the manifold legacies of authoritarian rule are not confronted, including privileged, non‐accountable military and security bureaucracies. The dangers of authoritarian rule within a formally democratic shell may be as great as, and more difficult to detect than, those of direct military reintervention.