The Repugnant Conclusion is a controversial theorem about population size. It states that a sufficiently large population of lives that are barely worth living is better than a smaller population of high quality lives. This is highly counter-intuitive. It implies that we can improve the world by trading quality of life for quantity of lives. Can it be defended? Christopher Cowie explores these questions and unpacks the controversies surrounding the Repugnant Conclusion. He focuses on whether the truth of the Repugnant Conclusion turns - as some have claimed - on the uncomfortable claim that many people’s lives are actually bad for them and that even privileged people lead lives that are only just worth living. Highly recommended for those interested in ethics, applied ethics and population studies The Repugnant Conclusion will also be of interest to those in related disciplines such as economics, development studies, politics and international relations.