THIS issue of the REVIEW marks the first time that an entire chapter has been devoted to construct validity. This presentation, therefore, includes not only a review of recent pertinent publications, but also a resume of the historical development of the concept with special attention to the influences of the philosophy of science and of theoretical psychology upon the psychometric concept of validity. Also treated are current trends in the rapprochement of the theory and methodology of experimental psychology and psychometrics; recent systematic and empirical developments in test construction pertinent to construct validity; and, in conclusion, an evaluation of the apparent heuristic values of the term and the method.Construct validity departs from classical notions of test validity in that it does not confine itself to the assessment of the extent to which a test score measures an outside criterion. Construct validity is concerned with the logical and empirical investigation of what psychological qualities a test measures (5,6,8,38,89). It is based upon the experimental evaluation of the behaviorally relevant aspects of a theory. Construct validity may be considered a special case of the general scientific methodology for giving inductive support to the hypothetical regions of a theoretical network (11,12,13,14,24,94).