During the past two decades, there have been several highly visible developments in education, including behavioral objectives, criterion-referenced test interpretations, the mastery model in instruction, performance-based instructional programs, competency testing, and accountability. This paper is an attempt to weave these various developments into a meaningful model of interrelationships and to explore the implications of that model in terms of teaching, testing, and grading. Major topics covered include: manifestations of individual differences, types of subject matter content, types of instruction, types of instructional objectives (behavioral minimal essential objectives and mentalistic developmental objectives), types of tests, types of test interpretations, and types of test scores. Juxtaposed to these topics, in a matrix format, are model tracks conceptualizing the following: (1) entire content of a small, closed domain that is readily specified in behavioral terms and content that is vital and masterable; (2) task readily specified in behavioral terms, but incapable of mastery or not important enough to merit mastery; and (3) content of large and/or open domain that cannot be specified in detail or mastered but can be illustrated in behavioral terms. The model is provided to enable practitioners to make decisions concerning which parts of a specific course fit the teaching, testing, and grading models of the three tracks. (TJH)