This publication focuses on the knowledge base of middle school teacher preparation emphasizing organizing principles that define an excellent middle grades teacher education program. It is designed to complement the National Council for Accreditation of Teacher Education (NCATE) and National Association of State Directors of Teacher Education and Certification (NASDTEC) standards, which focus on licensure, and those of the National Board for Professional Teaching Standards (NBPTS), which define advanced certification of excellent teachers. The document begins with a historical perspective on the preparation of middle grades teachers, including licensure, recent trends, and consensus program components. Part two discusses the "wise and experienced" middle grades teacher in relation to young adolescent development, curriculum, instruction, school organization, family and community relations, and teaching roles. Part three examines three components that make up an excellent middle grades teacher preparation program within the context of school site delivery. These elements include the foundations of a teacher education program, subject area study or teaching field preparation, and elements of middle grades specialization. The document concludes with a brief discussion of the future of middle grades teacher preparation and the role of these organizing principles. (Contains 49 references.) (ND)