One of the greatest challenges posed to the student of Avicenna's psychology is whether he upholds a hylomorphic or dualistic conception of the soul. The hylomorphic position is the one espoused by Aristotle, in nuce that the soul is the entelecheia, or substantial form, of the body considered as matter. The dualistic position is that the soul is a separate substance that controls the body, itself also a substance. The goal of this essay is to determine the full complexity of Avicenna's position, by dissecting four of his great psychological works, each from a different point in his career: The Compendium on the Soul, The Origin and the Return, The De Anima from The Cure, and On the Rational Soul. Ultimately, we contend herein that the method we employ in solving this paper's central problem can serve as a guide to resolving other such problems in Avicenna's philosophy.