Chapter 1 begins by briefly setting the context of the South Korea–United States alliance and reviewing its history. The alliance began as a product of the Cold War that over the years evolved from an asymmetric, patron–client relationship to one that resembles a partnership. Grounded in alliance theory, this book is a study of how the alliance has changed over time and the factors that have contributed to that evolution. Few studies have examined how alliances change and adapt as a result of endogenous factors, particularly how the power relations spurred by the economic growth and political development of junior partners have affected the alliance. In South Korea’s case, democratization, economic growth, and a desire to be a more active player in international relations have played an important role in alliance transformation.