This dissertation is a biography of Charles Birch, a renowned population ecologist, religious philosopher and environmental advocate who invented the phrase (and helped spark a movement toward) “ecological sustainability.” The chief intellectual merits of the project are its contributions to the history of ecology, the history of evolutionary thought, and the history of the relationship between science and religion during the 20^th century. A major goal of this study is to explore the connections between Birch’s Whiteheadian “process” theology, which was explicitly intended to adapt Christian faith to the findings of modern science, and Birch’s preoccupation with ecology/environmental biology. The project proposes as a working hypothesis that Birch’s scientific and religious-philosophical pursuits were rooted in a common worldview, guided by common moral and philosophical principles, and therefore sources of common solutions to current social problems. Birch’s ecological worldview professed the existence of a dynamic interconnectedness between all living things, and called on younger generations to recognize that by adopting an “ethics of ecology” (or “life-centered” ethics) they could avert many problems symptomatic of an industrial, technology-driven world, and do so without falling into old ideological traps of religious conservatism and scientific determinism (what he saw as the polar extremes). While Birch’s synthesis of ideas was unique, the problems he sought to address during his life were truly universal. Society today continues to search for a healthy relationship between its scientific pursuits and ecological responsibilities, as well as between its scientific pursuits and religious foundations. This dissertation project will aid in broadening our understanding of how these relationships developed over the past century and how they reached their present status within 21^st-century society.