In this innovative study of the relationship between persons and their bodies, E. J. Lowe demonstrates the inadequacy of physicalism, even in its mildest, non-reductionist guises, as a basis for a scientifically and philosophically acceptable account of human beings as subjects of experience, thought and action. He defends a substantival theory of the self as an enduring and irreducible entity - a theory which is unashamably committed to a distinctly non-Cartesian dualism of self and body. Taking up the physicalist challenge to any robust form of psychophysical interactionism, he shows how an attribution of independent causal powers to the mental states of human subjects is perfectly consistent with a thoroughly naturalistic world view. He concludes his study by examining in detail the role which conscious mental states play in the human subject's exercise of its most central capacities for perception, action, thought and self-knowledge.