A lively, accessible overview of the important people, organizations, events, and themes in the United States between 1898 and 1917, the Historical Dictionary of the Progressive Era is the most comprehensive and coherent reference work on the Progressive Era.

Catherine Cocks is an independent scholar. Peter Holloran is associate professor of history at Worcester State College. Alan Lessoff is professor of history at Illinois State University and editor of the Journal of the Gilded Age and Progressive Era.