This booklet examines four philosophical approaches which undergird the tenets of middle school: (1) invitational education; (2) democratic schools; (3) constructivist teaching; and (4) reflective teaching. An introduction discusses the history of the middle school movement, lists characteristics of exemplary middle schools, presents recommendations of the Carnegie Task Force for middle school operation, and summarizes the functions of middle schools. A chapter is devoted to each of the philosophical movements; in each chapter, the philosophy is defined, its major principles elucidated, and its implementation at the middle school level discussed. Invitational education involves working from a language that expresses care, reflected through modeling, dialogue, practice, and confirmation. The basis of democratic schools is to make a commitment to conditions and processes that make mutual respect and continuous dialogue possible for all participants. Constructivist teaching entails a belief that learning is a social process in which teachers help learners to internalize and reshape information or reinvent their knowledge. Reflective teaching requires teachers to think seriously about the origins and consequences of their pedagogy and about the situations and constraints embedded in the instructional, curricular, school, and social contexts in which they work. The four philosophical movements are complementary and provide a sound basis for educators to provide meaningful experiences for young adolescents. (Contains 43 references.) (Author/KDFB)