This article examines the evolution of diversity in the Journal of Applied Psychology. To begin, we explore foundations of the concept of diversity, including its appearance in both applied contexts and the scholarly literature. We then review the literature on diversity, including the development of its conceptualization and operationalizations over time, in the Journal and in the field of applied psychological science at large. We also examine the processes underlying the effects of diversity, and specific outcomes of diversity in organizations. To conclude, we offer a future research agenda that highlights diversity-related topics and issues important for advancing an understanding of diversity and moving the field forward, especially within the Journal. This work makes several contributions to research on diversity in organizations. First, we provide a lens for examining change in the study of diversity over time as well as a critical examination of the benefits and challenges associated with these changes. Second, we review the underlying mechanisms and key contextual influences on diversity effects in organizations. Third, our review examines the explanatory power of current diversity research and then uses this to develop a research agenda. By organizing the broad body of literature that exists on diversity, our article offers a sharp picture of what gaps in knowledge exist and where future research should focus.