The Trolley Problem is one of the most intensively discussed and controversial puzzles in contemporary moral philosophy. Over the last half-century, it has also become something of a cultural phenomenon, having been the subject of scientific experiments, online polls, television programs, computer games, and several popular books. This volume offers newly written chapters on a range of topics including the formulation of the Trolley Problem and its standard variations; the evaluation of different forms of moral theory; the neuroscience and social psychology of moral behavior; and the application of thought experiments to moral dilemmas in real life. The chapters are written by leading experts on moral theory, applied philosophy, neuroscience, and social psychology, and include several authors who have set the terms of the ongoing debates. The volume will be valuable for students and scholars working on any aspect of the Trolley Problem and its intellectual significance.