The purpose of this paper is to clarify the seemingly discrepant views of test theorists and test developers about terminology related to the evaluation of test content. The origin and evolution of the concept of content validity are traced, and the concept is reformulated in a way that emphasizes the notion that content domain definition, relevance, and representation are necessary and fundamental qualities on which all tests should be evaluated. An important area of convergence for test theorists and test developers has been that adequately defining and representing the construct measured is of critical importance. Broad definitions have asserted that content validity is concerned with test and response properties, but narrow definitions limit content validity to investigations of items, tests, and scoring. Future descriptions of test validity must emphasize the important role of content validity in the construction and evaluation of test. Theories and applications of content validity belong within the framework of construct validity. (Contains 1 table, 2 figures, and 69 references.) (SLD)