Modern American Environmentalists profiles the lives and contributions of nearly 140 major figures during the twentieth-century environmental movement. Included are iconic environmentalists such as Rachel Carson, E. O. Wilson, Gifford Pinchot, and Al Gore, and important but less expected names, including John Steinbeck and Allen Ginsberg.

The entries recount how each individual became active in environmental conservation, detail his or her significant contributions, trace the influence of each on future efforts, and discuss the person's legacy. The individuals selected for the book displayed either an unparalleled commitment to the conservation, preservation, restoration, and enhancement of the natural environment or made a major contribution to the growth of environmentalism during its first century.

With a foreword by environmental historian Everett I. Mendolsohn, a time line of key environmental events, a bibliography of groundbreaking works, and an index organized by specialization, this biographical encyclopedia is a handy and complete guide to the major people involved in the modern American environmental movement.

George A. Cevasco (1924–2008) was a professor of English at St. John's University and the author or editor of numerous books, including Biographical Dictionary of American and Canadian Naturalists and Environmentalists and The 1890s: An Encyclopedia of British Literature, Art, and Culture. Richard P. Harmond was an associate professor of history at St. John's College. He coedited Biographical Dictionary of American and Canadian Naturalists and Environmentalists and coauthored Environmentalism and the Government.