Methodology The Ledger represents a synthesis of leading research on conceptualizing, explaining, and forecasting political instability. The definition established by the Political Instability Task Force (PITF) is employed.1 This definition guided the PITF’s compilation of state failure events during 1955-2006, which encompass a wide variety of types, including revolutionary wars, ethnic wars, adverse regime changes, and genocides or politicides. While the set of events is heterogeneous, they share a fundamental similarity: their onset signals the arrival of a period in which government’s capacity to deliver core services and to exercise meaningful authority has been disrupted, threatening its overall stability.