Nearly two decades of research has taught some powerful lessons about how to design and implement meaningful and effective professional development for teachers. This newsletter examines the characteristics of high-quality professional development and offers some suggestions for improving its impact and effectiveness. For reform efforts centered on improving student achievement to be successful, teachers need to have the necessary skills, tools, and support. Simply trusting that structural and logistical changes will translate into significant improved learning is wishful thinking. Teachers need concrete, continuous professional development to hone their current skills and learn new ones. And they need to be respectfully treated as adult learners who bring skills and experiences to meet the challenge of increasing student achievement. [This document was produced by The Center for Comprehensive School Reform and Improvement, administered by Learning Point Associates in partnership with the Southwest Educational Development Laboratory (SEDL) and WestEd, under contract with the Office of Elementary and Secondary Education of the U.S. Department of Education.]