Timothy O'Connor is one of the most prominent defenders today of the "agent causal" theory of free will. This thesis evaluates his theory, primarily as it is presented in his book Persons and Causes: The Metaphysics of Free Will. Three sets of issues are explored in the thesis. First, there are issues pertaining to the core idea of agent causation, such as how it contrasts with event causation and whether it can withstand a classic objection leveled by C. D. Broad. Second, various aspects of O'Connor's noncausal theory of reasons explanations, which fleshes out his action theory, are considered, along with several objections thereto. Finally, O'Connor's emergentist and property dualist views, which provide a foundation for his theory of free will, are assessed, and an alternative dualist framework is proposed. The thesis concludes that O'Connor's theory is largely unsatisfactory, although it offers valuable leads in some important areas.