Featuring a diverse and distinguished group of scholars, this volume provides a much-needed, research-based analysis of nonsupervisory, school-based, instructional leadership. Frequently referred to as teacher leaders, specialists, or coaches, these new positions have the potential to provide teachers with the skills and knowledge necessary for continued instructional improvement and, ultimately, enhanced student learning. This authoritative collection presents both qualitative and quantitative evidence on the enactment, design, conditions, constraints, and successes of this type of instructional leadership. This book offers important lessons for the improvement of policy and practice.