The introduction to this anthology connects a diverse collection of essays that examine the 1940s as the critical decade in the United States’ ascendance in the Pacific Rim. Following the end of World War II, the United States assumed the hegemonic role in the region when Japan’s defeat created military and political vacuums in the region. It is in this context that this anthology stands not only as a précis of current scholarship but also as a prospectus for future research. The contributors’ chapters eschew the traditional focus on military operations that has dominated the historiography of 1940s in the Pacific Basin and East Asia. Instead, the contributors venture into areas of race, gender, technology, culture, media, diplomacy, and institutions, all of which add nuance and clarity to the existing literature of World War II and the early Cold War.