In this book, the authors provide an overview of adult learning and its impact on professional development. The chapters provide a theoretical foundation along with practical advice on implementing team-based professional development among educators within school districts which will lead to true systemic reform. The following seven chapters are presented: (1) What If? The Case for Team-Based Professional Development--A New Model for Professional Growth; (2) How Did We Get Here? Design Options for a Professional Development Continuum; (3) Teachers Who Asked What If? Criteria for Successful Team-Based Professional Development; (4) Can You Do This? Successful Programs; (5) Taking One Step At A Time: Initiating and Implementing Team-Based Professional Development; (6) How Do You Know It's Working? Organizing and Monitoring Professional Development Programs; and (7) What If It Happens? Institutionalizing and Sustaining Team-Based Professional Development.