There is no single, eternal, and immutable “truth” about past events and their meaning. Revisionism is the essence of historians’ work. Their interpretations of the past are subject to change in response to new evidence, new questions asked of the evidence, and new perspectives gained by the passage of time. This chapter demonstrates the importance of generational change as a source of revisionist interpretations of the past. The social upheaval of the 1960s in America created a generational cleavage and led to rejection of the orthodox interpretation of the bomb’s use by young historians. We see how both personal and social conditions influenced the new generation’s interpretations. Gar Alperowitz’s flawed Atomic Diplomacy (1965), which argued that the bomb’s purpose was to intimidate the Soviet Union, was the most high-profile work, but other revisionists had different objections to the orthodox interpretation. The later revisionist analysis of Tsuyoshi Hasegawa’s Racing the Enemy (2005) based on new foreign language materials offered a more informed and nuanced revisionist view. The revisionists succeeded in opening a spectrum of new issues in the controversy.