Part of the “boundary work”(Gieryn, 1983) throughout the history of psychology has been to divide the discipline into camps of “basic” and “applied” researchers who take different methodological approaches to construct knowledge. Each “side” has come up with different processes for conceptualizing, constructing, and evaluating the legitimacy of knowledge claims, processes that have implications for applying research insights to practical issues in society. In this article, I review and synthesize research on the history of knowledge construction in both basic and applied psychology, and the implications of their respective methodological practices for their perceived legitimacy. I then discuss how the lessons learned from the past can be leveraged to address the current crisis of confidence in the “credibility revolution” era (Vazire, 2018), as well as the field’s perceived legitimacy to external stakeholders. Finally, I end with recommendations for structural changes to improve the credibility and legitimacy of our field’s findings as well as their relevance for achieving our public psychology goals.(PsycInfo Database Record (c) 2022 APA, all rights reserved)