Bertrand Russell is widely considered to be one of the founders of analytic philosophy, epistemology, and philosophy of science. Individuals have usually stressed his early philosophical contributions as seminal in this regards. But Russell also had another side–a naturalistic side–leading him towards a naturalistic epistemology and naturalistic philosophy of science of the type Quine later made famous. My goal is to provide an outline of Russell's naturalistic epistemology and the underlying philosophical motivations for such a move. After briefly presenting Russell's conception of the nature of philosophy, I sketch his theory of philosophical method, which is a version of the method of analysis. This provides the underpinnings for a discussion of his Naturalistic Epistemology, which led him to adopt a version of a behavioristic epistemology. Although Russell vacillated on the question of the adequacy of such an account, it provided a major element in his later philosophical views. I suggest that we must reevaluate our conception of the history of analytic philosophy and, in particular, our understanding of Russell's place in the history of 20th century philosophy.