F or the last 15 years, research on the study of work as a calling has grown exponentially, spanning the fields of counseling, vocational, and industrial and organizational (I/O) psychology as well as management, philosophy, and religion. Although estimates vary on how many publications on calling exist, several of the most influential papers on this topic have each been cited over 1,000 times (Dik & Duffy, 2009;Hall & Chandler, 2005;Wrzesniewski et al., 1997), with those citation counts consistently growing from year to year. However, one important piece missing from this literature has been an overarching theory. Duffy et al. (2018) attempted to address this limitation with the publication of the work as calling theory (WCT). The primary aim of the theory was to explain how perceiving a calling links with living a calling and, in turn, the associated outcomes that occur when one lives out their calling. In the current chapter, we aim to (a) provide an overview of WCT, (b) highlight studies that have used it as a partial or full framework, (c) recommend ideas for future research using the theory, and (d) explore the theory's implications for career counseling practice.