Compassion is widely regarded as an important moral emotion - a fitting response to various cases of suffering and misfortune. Yet contemporary theorists have rarely given it sustained attention. This volume aims to fill this gap by offering answers to a number of questions surrounding this emotion. These questions include: What is the nature of compassion? How does compassion differ from other emotions, such as empathy, pity, or gratitude? Is compassion a virtue? Can we have too much compassion? How does compassion influence other mental states (desires, motivations, beliefs, and intentions) and behaviour? How is compassion influenced by the environment? Must compassion be deserved? Can one be moral while lacking the capacity for compassion? Compassion, like other emotions, has many facets - biological, social, psychological and neural, among others. The contributors to this volume will draw on a variety of disciplines and methods in order to develop a more systematic and comprehensive understanding of this often-neglected moral emotion.