Most military alliances have tended to be temporary expedients, aimed at gaining short-term advantage or lulling potential enemies into complacency. NATO is different: it was designed from the start to be permanent and has endured for over 60 years. Thies, a political scientist, argues on the basis of case studies drawn mostly from the Cold War that two factors account for this staying power: the world's bipolar distribution of power in the second half of the twentieth century and the existence of a homogeneous political ideology among NATO's members. One wonders if Thies' explanation can be simplified further, since two decades after the Cold War, NATO lives on, even though bipolarity is gone. Perhaps the organization owes its staying power simply to the shared values and institutions of liberal democracy: Western governments are thus left with little to fight over and much to cooperate on. Why NATO Endures provides a useful reminder of NATO's essential stability in the face of deep fissures over many small issues. What might need to be explained are the policy writings of the 1990s and the first decade of this century that have heralded the collapse of an institution that shows no sign of disappearing.