One of the most important things leaders do is communicate. Though research on leaders’ communication has been active for half a century, to date there has been little effort to review it comprehensively and systematically. In this paper we review 260 articles that use leaders’ actual communication (textual, aural, and video) as data. We group these studies into four broad categories as a function of whether they focus on the (1) content and style, (2) antecedents, or (3) outcomes of leader communication, or (4) use leaders’ communication data to infer leader attributes that are unrelated to communication. We document how empirical methodologies to analyze verbal and nonverbal communication have advanced over time, with early labor-intensive coding methods joined by more automatic and computer-based approaches, including Machine Learning. We conclude by discussing how this research has extended and enriched dominant leadership theories and suggest future opportunities for studies that use leader communication as a focal construct or input.