Ephraim George Squier and the Development of American Anthropology is an intellectual biography of Ephraim Squier (1821–88) and his contributions to the development of the nascent disciplines of archaeology and anthropology. During his career, which spanned the years 1845–77, Squier consistently articulated the need for a more holistic and integrated approach to the study of humankind. Although Squier is best known today for the classic book he coauthored with Edwin H. Davis, Ancient Monuments of the Mississippi Valley, Terry A. Barnhart shows that Squier’s fieldwork and interpretive contributions to archaeology and anthropology continued over the next three decades. He turned his attention to comparative studies and to fieldwork in Central America and Peru. He became a diplomat and an entrepreneur yet still found time to conduct archaeological investigations in Nicaragua, Honduras, and Peru and to gather ethnographic information on contemporary indigenous peoples in those countries. He published an important and still not fully appreciated comparative study, The Serpent Symbol, and the Worship of the Reciprocal Principles of Nature in America, which attempted to systematically account for parallel cultural developments that he attributed to the psychic unity of humankind. A wealth of unpublished sources illuminate Squier’s wide-ranging interests and controversial career, his intellectual circle, and the public interests of an energetic and expansive American nation. Terry A. Barnhart offers us the first intellectual biography that explores the personal and professional life of a remarkable and significant figure in the history of American anthropology.