Introducing the tracking of terrorist organization splintering (TOTOS) dataset

What explains why some splinter groups are highly violent, capable, and durable, while others are not? Although existing scholarship provides important insights into the causes and consequences of terrorist group splintering, it provides contrasting – and at times contradictory – explanations of splinter behavior. This research note resolves this contradiction using the Tracking of Terrorist Organization Splintering (TOTOS) dataset. TOTOS is a new and original dataset that traces the lineage of terrorist organizations-both domestic and transnational-that were active between 1970 and 2020, identifying 144 original parent organizations and 370 splinter groups comprising 138 families. Using a novel, theory-based typology on terrorist group splintering, I distinguish four types of terrorist group splinters: divorce, reformation, challenger, and familial. I provide compelling descriptive and statistical evidence that disaggregating splinters reconciles competing findings about the consequences of splintering on violent behavior. Beyond advancing the literature on terror group formation and splintering, the new information in this research note will help scholars further explore why some groups are more violent, more willing to engage in activities that win the hearts and minds of host populations, and more likely to endure.