Courage is a well-praised but little-researched virtue, defined as voluntarily facing personal risk in pursuit of a worthy goal. Scientific research on courage has been steadily gaining momentum for the past decade. After providing a historical perspective, this chapter discusses a wide range of topics from modern courage theory. The key dimensions of courage (volition, goal, and risk) are introduced, and distinct types of courage are defined, based on how they differ on these key dimensions. Unique features present in select types of courage are also examined, including felt responsibility to act and the presence of fear. Several models for conceptualizing and evaluating courageous actions are reviewed, featuring a comparison of process and accolade courage. Psychological states and situational factors affecting courageous actions are considered, including emotional states, personal values, and social influences. Measurement tools for courage are described and appraised, and future directions for research and practice are discussed.