A three-dimensional model designed to depict the interrelationships among evaluation procedures, development systems, and reward structures as they affect professional personnel is offered as a research tool in this paper. The model is intended to aid in describing and understanding the productivity of professional personnel and to enhance the development of procedures related to accountability. Key terms in the field of professional personnel evaluation are defined, assumptions underlying the model are listed, and the model is described and illustrated in the paper. (Author/PGD)