As NATO’s first hostile offensive military action, Operation Allied Force placed new demands and pressures on the Alliance. Those pressures and demands offer an opportunity to answer critical questions regarding Alliance politics: How much autonomy do the Alliance members have? Does the U.S. dictate Alliance policy? Can the Alliance function politically while engaged in combat? Contributors explore the experience of NATO’s members individually as well as in terms of implications for theories of alliances. More fundamentally, the contributors to this volume ask whether Operation Allied Force reflected a consensus among NATO’s members, or whether some members were “Forced Allies.”