Part of the Ontario PrincipalAEs Council Leading Student Achievement Series, this book is designed to help school leaders get started on using data to inform, shape, revise and assess their school improvement plan. In this practical guide, the author defines what data is and is not, explains the roles of the principal in leading the data-based school improvement planning process, and outlines how a principal can successfully introduce data-driven school improvement planning, create a culture of using broadly based data to inform all decisions, and use and refine the data-driven school improvement planning cycle.