Tricia L. Bacon and Elizabeth Grimm provide a groundbreaking analysis of how religious terrorist groups manage and adapt to major shifts in leadership. They demonstrate that founders create the base from which their successors operate. Founders establish and explain the group’s mission, and they determine and justify how it seeks to achieve its objectives. How successors then position themselves in terms of the founder shapes a terrorist group’s future course. They examine how and why different types of successors choose to pursue incremental or discontinuous change. Bacon and Grimm emphasize that the instability surrounding succession can place a group at its most vulnerable—the precise time to explore options to weaken or defeat it.