This dissertation examines prizefighting and other popular amusements in late-nineteenth and early-twentieth century San Francisco both to construct a social history of participants, spectators, and consumers and to illuminate the relationship between popular amusements and politics. Turn-of-the-century San Franciscans promoted and challenged class, racial, and gender identities in the spaces of popular amusement, as in controversies over women's attendance at prizefights. At the same time, these identities were displayed through the production of particular forms of public culture, as in the racialized scripts promoted in the screenings of the film The Birth of a Nation and the suppression of the film version of the Jack Johnson-Jim Jeffries boxing match, in which a black man bested his white opponent. But while such people as athletes, sports enthusiasts, moviegoers, and dance-hall denizens sought entertainment, self-assertion, and sometimes a livelihood from popular amusements, politicians and social reformers often made these civic pastimes the focus of debates about what constituted a modern and progressive city. Would San Francisco's vibrant world of prizefighting persist amid politicians' attempts to sell the city as the modern and progressive choice for the 1915 Panama-Pacific International Exposition? Would female dance instructors and prizefighters be able to keep working in San Francisco after a gang of boxers brutally assaulted two women they met in one of the city's most popular dance halls and reformers took up the cause? Much more than a study of urban Americans at play, then, this dissertation uses popular amusements to explore the most pressing and controversial issues of the era: women's rights, race relations, class conflict, ethnic identity, and moral reform.