The purpose of the study reported in this five-chapter document was to develop a model of differentiated teaching personnel based on student learning needs and to test the rationale for developing that model. The resultant semantic model (presented and illustrated in chapter 4 of the report) is designed to provide for effective interaction between teaching style and student learning while at the same time providing the kind of growth and advancement opportunities which will enable and encourage teaching personnel to remain in the profession. The model differentiates secondary school staffing responsibilities according to the following: (1) general phases of a total school program (instruction, curriculum, facilities, testing, teacher evaluation, and responsibilities for students); (2) types or modes of learning-management activities under each phase (for example, large-group, small-group, or individually directed learning under the instructional phase); and (3) levels of responsibility in each activity (major, subordinate, or planning). Four submodels (developed to define teaching responsibilities of each of four kinds of teachers--assistant, associate, senior, and master teacher) are presented to illustrate the applications of the model to problems of staff utilization. Procedures by which the model rationale was validated are described in chapter 5. (Author/ES)