Behavioral strategy has emerged as one of the most important currents in contemporary strategic management. But, what is it? Where does it come from? Why is it important? This Element provides a review of key streams in behavioral, interpreting behavioral strategy as a consistently microfoundational approach to strategy that is grounded in evidence-based insight in behaviors and interaction. We show that there is considerable room for furthering the microfoundations of behavioral strategy and point to research opportunities and methods that may realize this aim. The Element is of interest to strategy scholars in general, and to Ph.D. students in strategy research in particular.