Physicalism is a program for building a unified system of knowledge about the world on the basis of the view that everything is a manifestation of the physical aspects of existence. Jeffrey Poland presents a systematic and comprehensive exploration of the philosophical foundations of this program. He investigates the core ideas, motivating values, and presuppositions of physicalism; the constraints upon an adequate formulation of physicalist doctrine; the epistemological and modal status, the scope, and the methodological roles of physicalist principles. He reviews and evaluates major objections to the program, and considers its significance for philosophy, science, society, and individual persons. He also examines the relations between physicalism and other philosophical positions, such as realism, empiricism, and relativism, and suggests that physicalism is compatible with a tolerant pluralism in the philosophical, cultural, and personal domains.