The 13 papers in this collection, which served as the basis for policy recommendations in "What Matters Most," a major report of the National Commission on Teaching and America's Future, synthesize important research in the fields of teaching and teacher education. Emphasized throughout is the importance of a significant and sustained investment in well-educated professional teachers. Following an introductory chapter, by Gary Sykes, "Teaching as the Learning Profession," papers are grouped into four sections: teacher education, teacher professional development, organizations for teacher learning, and policies for teacher learning. The papers are: (1) "Developing Practice, Developing Practitioners: Toward a Practice-Based Theory of Professional Education" (Deborah Loewenberg Ball and David K. Cohen); (2) "Aligning Teacher Education with Contemporary K-12 Reform Visions" (Magdalene Lambert and Deborah Loewenberg Ball); (3) "The Role of Preservice Teacher Education" (Mary M. Kennedy); (4) "Preparing Teachers for Diversity: Historical Perspectives, Current Trends, and Future Directions" (Gloria Ladson-Billings); (5) "The Essentials of Effective Professional Development: A New Consensus" (Willis D. Hawley and Linda Valli); (6) "Teacher and Student Learning: Strengthening Their Connection" (Gary Sykes); (7) "Teacher Recruitment, Selection, and Induction: Policy Influences on the Supply and Quality of Teachers" (Linda Darling-Hammond et al.); (8) "Organizing Schools for Teacher Learning" (Judith Warren Little); (9) "Investing in Teacher Learning: Staff Development and Instructional Improvement" (Richard F. Elmore and Deanna Burney); (10) "Networks and Reform in American Education" (Ann Lieberman and Maureen Grolnick); (11) "Organizing the Other Half of Teaching" (Julia E. Koppich and Charles Taylor Kerchner); (12) "The Frame and the Tapestry: Standards-Based Reform and Professional Development" (Charles L. Thompson and John S. Zeuli); and (13) "Investing in Teaching as a Learning Profession: Policy Problems and Prospects" (Linda Darling-Hammond and Milbrey Wallin McLaughlin). (Individual papers contain references.) (DB)