The story of U. S. nuclear testing between 1945 and 1963 is a vivid and exciting one, but also one of profound importance. It is a story of trailblazing scientific progress, weapons of mass destruction, superpower rivalry, accidents, radiological contamination, politics, and diplomacy. The testing of weapons that defined the course and consequences of the Cold War was itself a crucial dimension to the narrative of that conflict. Further, the central question of why conduct nuclear tests was debated among politicians, generals, civilians, and scientists. The book focuses on this question and on the United States as it was the first nation to test and use nuclear weapons. The U.S. also has remained ahead of all other powers in achieving significant testing milestones and has conducted more nuclear tests than any other nuclear power. It first argues that nuclear weapons testing was for the most part a rational state act that provided essential information about nuclear weapons and their use. This information, in turn, illuminated other important issues, such as the details of test cessation agreements.Second, crucial to the history of nuclear testing as a rational state act was the idea of its normalization, a process that began under Truman. The norm of nuclear testing as an acceptable state action however was undermined by Eisenhower's moratorium of 1958-1961. The ensuing political dilemma surrounding the tests led under Kennedy found a resolution only through the Limited Test Ban Treaty. Lastly, the book argues that part of the reason why Washington accepted the Limited Test Ban Treaty in 1963 was because it recognized that it had accomplished all that could realistically be expected from atmospheric weapons testing. Overall, it was a victory for those who argued in favor of national security over diplomatic and environmental costs that normalized nuclear weapons tests. Today, as states continue to pursue nuclear weaponry, nuclear testing remains an important political issue in the 21st century, making the study of its history vital.