This publication, designed to help schools develop successful middle school programs and establish long-range goals for educating early adolescents, is divided into two parts. Part I examines the conceptual development of the effective middle school. It begins with a review of recent effective schools research and goes on to list and define 11 effective middle school characteristics. An effective middle school: (1) features a program responding to early adolescents' physical, intellectual, social-emotional, and moral needs; (2) has a set of program guidelines; (3) possesses a curriculum plan that includes organized knowledge, skills, and personal development activities; (4) has a clearly established program of studies based on exploration and student growth opportunities; (5) builds on elementary education strengths while preparing students for high school; (6) employs teachers using appropriate teaching strategies; (7) creates teaching teams using block-of-time scheduling; (8) emphasizes staff members' guidance and counseling function by providing a supportive climate; (9) promotes flexible scheduling to meet students' varying needs; (10) actively involves parents; and (11) evaluates the program regularly. Part I also explains the change process and presents a staff development model for successful program implementation. Part II features a comprehensive model for implementing the 11 effective school characteristics and presents a specific plan for each programmatic piece. Included are a review of the conceptual basis for each characteristic, techniques to organize administrative/supervisory leadership, goal-setting procedures, and assessment methodologies. (MLH)