Standard interpretations of the history of public health in New York City in the twentieth century describe either the decline or the growth of the importance accorded to public health activities. To the contrary, public health has, paradoxically, both declined in salience and attracted increasing resources. This article describes the politics of public health in New York City since the 1920s. First it describes events in the history of public health in the context of events in the economy and in city, state, and national politics. Then it proposes three descriptive models for arraying the data about public health politics: accretion, reform, and crisis. Next it describes how the politics of AIDS in New York City in the 1980s was a consequence of the history that produced these three political styles. Finally, it argues that the three political styles are generalizable to the history of public health throughout the United States in the twentieth century.