The stage was set for the emergence of cool as a cultural phenomenon in the early 1940s by a series of sweeping transformations in the first decades of the twentieth century. The figures in this first section were not called cool in their day but were leading exemplars of new energies that were changing the social contours of American life. A fresh rebelliousness was revealed in the new film capital of Hollywood, in modernist literature and art, in emerging youth entertainments, and in a new music called jazz. The advent of technologies such as radio, film, and the automobile and the increasing diversity in America’s booming cities accelerated the pace of change. Though Prohibition in the 1920s sought to regulate American morality by ending the consumption of alcohol, this period saw the expression of a new independence among young people and others historically on the margins of public life. In particular, both African Americans and women sought and began to attain freedoms long denied. Cool has long denoted a person’s sense of calm and composure. Charismatic individuals such as those featured here contributed greatly to the changing mores in American society before World War II. Cool would ultimately serve as the term that would describe this new rebel.