During the last twenty-five years, the dominant educational reform initiatives in the US have operated under the partially misguided conventional wisdom that the educational system is loosely coupled. Decades of educational reform efforts have focused on tightening the system, including implementing curriculum standards, statewide student testing, and evaluation of the school, teachers, and principals. Based on empirical results, we argue that the educational system is neither loosely nor tightly coupled, but bifurcated in that (to borrow a metaphor from geoscience) it is comprised of two tectonic plates. The first plate consists of the state, district, and school levels, and the second is the classroom, with a fault line between them. The theory of the bifurcated system raises the key question of how to bridge the fault line. Two principles are proposed for school improvement in the bifurcated context. The first principle is to integrate principal and teacher leadership, effectively bridging the fault line in both directions. The second principle is the school renewal process, helping transform the school improvement practice by introducing the idea of implementation integrity.