The successful resolution of violent intrastate conflict often depends on rebels being willing to accept peace settlements. However, some rebels refuse to do so, instead forming splinter organizations that perpetuate and escalate violence to undermine peace. Why Rebels Reject Peace provides novel theory and evidence from one of the longest running conflicts in modern history – the fight for a united and independent Ireland – to show how rebels' personal experiences with the adversary shape the choice to reject peace. The book narrows in on individual decision-making within rebel organizations to show how governments and rebel communities bear responsibility for creating extremists. The book also outlines when and how governments can design peace settlements to better satisfy rebel organizations. Ultimately, the book proves how government actions, both on the battlefield and at the negotiating table, shape when and why rebels reject peace.