This chapter revisits the definition of empathy and delineates it from other routes to social understanding. It examines the theoretical and neural underpinnings of concepts such as emotion contagion and mimicry, which can be thought of as antecedents of empathy, and compassion and empathic distress, which are introduced as consequences of empathy. The chapter reviews the major contributions of psychological research to the understanding of empathy and its relation to prosocial behavior. It then focuses on how research in social neuroscience has advanced our understanding of empathy in the human brain. The chapter stresses the specific role of the insula as a neural structure that processes interoception and empathy. It describes factors that modulate the experience of empathy for pain along with their neural underpinnings. Finally, the chapter discusses initial findings from social neuroscience research focusing on more positive aspects of empathy, such as compassion.