This chapter explores the profound transformations and the establishment of American hegemony during the 1990s, a period often referred to as the “unipolar moment” following the end of the Cold War. It examines the multifaceted dominance of the United States in global politics, economics, culture, and technology, highlighting both the unparalleled influence of the nation and the widespread optimism that defined the decade. While the era was marked by confidence in American leadership, it was also accompanied by challenges and criticisms. This chapter reflects on the promise and perils of U.S. hegemony, situating the unipolar moment within the broader trajectory of American history and emphasizing its transformative impact on the global order. Additionally, the chapter analyzes domestic and international perceptions of the United States during this time. While many admired its technological advancements and cultural exports, concerns emerged about the homogenizing effects of American-led globalization. The discussion also addresses the mixed global reactions to U.S. foreign policy, examining both its role in maintaining global stability and the anxieties it provoked regarding interventionism and geopolitical dominance.