Alliances are promises of cooperation, but allies typically have to ba
rgain over what policy should be adopted when a given contingency aris
es. Whether this bargaining leads to collaborative outcomes and what f
orm cooperation by allies takes have important implications for the ef
fectiveness of an alliance. Neorealism and neoliberal institutionalism
, the author argues, do not provide adequate explanations for this pro
blem because they mischaracterize, or fail to come to grips with, the
bargaining process at work. To redress such shortcomings, the author t
urns to game theory, providing a general model of intra-alliance barga
ining. The model's insights are then used to interpret the historical
record on U.S. Bosnia policy from 1991 until the fall of 1995. The aut
hor shows how domestic and international considerations affected the p
references and beliefs of the Bush and Clinton administrations. These
led, as suggested by the model, to the U.S. tendency to avoid bargaini
ng hard with the NATO allies and to pursue compromise strategies with
them in the Bosnian crisis.