Every 26 seconds in the United States, a teenager drops out of school. A well implemented early warning system can help educators and others identify students at risk of dropping out and assign and monitor interventions to keep them on track for graduation. This book summarises what is known about early warning system implementation and describes how states, districts, and schools can draw on the research to inform their work locally. It provides evidence-based recommendations for use by educators addressing the challenge of reducing student dropouts.