How do we define compassion? Is it an emotional state, a motivation, a dispositional trait, or a cultivated attitude? How does it compare to altruism and empathy? Chapters in this Handbook present critical scientific evidence about compassion in numerous conceptions. All of these approaches to thinking about compassion are valid and contribute importantly to understanding how we respond to others who are suffering. Covering multiple levels of our lives and self-concept, from the individual, to the group, to the organization and culture, The Oxford Handbook of Compassion Science gathers evidence and models of compassion that treat the subject of compassion science with careful scientific scrutiny and concern. It explores the motivators of compassion, the effect on physiology, the co-occurrence of wellbeing, and compassion training interventions. Sectioned by thematic approaches, it pulls together basic and clinical research ranging across neurobiological, developmental, evolutionary, social, clinical, and applied areas in psychology such as business and education. In this sense, it comprises one of the first multidisciplinary and systematic approaches to examining compassion from multiple perspectives and frames of reference. With contributions from well-established scholars as well as young rising stars in the field, this Handbook bridges a wide variety of diverse perspectives, research methodologies, and theory, and provides a foundation for this new and rapidly growing field. It should be of great value to the new generation of basic and applied researchers examining compassion, and serve as a catalyst for academic researchers and students to support and develop the modern world.