Three distinctions are usually made between norm- and criterion-referenced measures. They are: (1) their measurement forms, that is, student performance in relation to the performance of other students or with respect to some specific criterion; (2) general or specific kinds of objectives in which the measures are founded; and (3) their modes of construction, that is, reliance upon items that differentiate among students or items that reveal degree of mastery on a given objective. The results of examinations of how both kinds of measures are actually constructed and used, however, indicate that these kinds of distinctions are misleading and can weaken the overall value of the evaluation effort. It is recommended that, for evaluation purposes, the essential difference between norm- and criterion-referenced measures should not be viewed as an intrinsic measurement difference but rather as a question of the interpretation of that measurement's results. With respect to ongoing evaluation, it is suggested that both norm- and criterion-referenced interpretations are needed for such diverse purposes as (1) identifying program components needing improvement, (2) identifying students needing special attention, (3) providing the basis for accountability systems, and (4) determining whether a program is being implemented as planned. It is concluded that unless both kinds of interpretations are made, realistic evaluations cannot be made. (Author)