Evolutionary leadership theory (ELT) argues that humans possess specialized psychological mechanisms for solving coordination problems through leadership and followership. We discuss the evolutionary functions and psychological processes underlying leadership, and how to study leadership and followership from an integrated evolutionary perspective. An evolutionary perspective offers novel insights into major barriers to leadership effectiveness in organizations. These obstacles include (a) mismatches between modern and ancestral environments, (b) evolved cognitive biases affecting leader selection and decision-making and (c) innate psychological mechanisms designed to dominate and exploit other individuals. Understanding the evolved psychological mechanisms underlying leadership, in terms of adaptive functions, mismatches, and psychological processes, is critical for the development and integration of leadership theory, research, and practice.