A new model for preservice teacher education exemplifies recent developments in the field. It is based on specifications of instructional and program goals in terms of behaviors to be exhibited by the trainee in three broad conceptual areas which imply a hierarchy of teaching competencies: mastery of content knowledge produces subject matter competency; mastery of content knowledge plus behavioral skills produce presentation competency; mastery of both plus humanistic or personological skills produce professional decisionmaking competency. Appropriate instructional modes (e.g., programed and computer-assisted instruction, video tape models, microteaching, classroom simulation materials) have been developed to assist each trainee to achieve the competencies individually. Performance criteria reflect the differentiated roles candidates will assume in a professional staff, and training for flexibility will make teachers change agents for schools. Implications of these trends for school principals: (1) Inservice training should become an extension of competencies. (2) Refined performance criteria can allow selection and promotion processes to be more objective, and supervision truly diagnostic. (3) The principal's role will shift from disciplinarian and evaluator to organizer, director, and facilitator--creator of a flexible setting to nurture teacher innovation. (JS)