Chapter 2 examined a range of meanings of pluralism evident in contemporary psychology, providing a reminder of the problems that can arise when we unreflectively treat concepts as consistent in meaning across time and disciplinary contexts. In this chapter, we turn our focus exclusively to the pluralism of William James, yet a similar cautionary note is in order. Although it is commonplace to speak of an author’s “concept of x,” upon scrutiny one may find meanings of “x” to be variable in different texts or across phases of that author’s thought. Therefore, this chapter aims to follow the development of James’s uses of the term “pluralism” across the body of his work, including his notes and correspondence. Among the goals of the chapter are (1) to consider how James’s early uses of the term “pluralism” relate to later versions, (2) to distinguish any divergences in meaning, and (3) to inquire whether there are consistent themes across his writing that pertain to pluralism.1