For nearly 75 years, the North Atlantic Treaty Organization (NATO) has served as a critical foundation and a centerpiece of the security order shaping Europe. The aims and purpose of the organization have been repeatedly contested over the decades, as members of the Alliance in Europe and North America have argued about their policies, priorities, and the future of the European order. In light of contemporary debates over whether and to what extent NATO and its expansion eastward since 1989 contributed to the current Russian war of aggression against Ukraine, this roundtable brings together three historians to discuss the past, present, and future of the Alliance. In doing so, this session will bridge the problems of the past with the challenges unfolding in Europe today.