Central in interest and promise stands the psychological test. In so far as psychology has laid bare the fundamental qualities upon which achievement depends, its application has developed a series of tests to determine how the individual compares with the others or with the average in respect to this, that, and the other constituent quality. Professor Hollingworth presents the results of such analysis, both in relation to the variety of human traits and in the grading of individuals by reference to the measure of the quality which each possesses. The enumeration is at best provisional, but in its totality cannot go far wrong in establishing the measure of a man. It includes the qualities which can hardly be determined otherwise than by an impressionistic judgment, as well as those appraised by actual achievement under test. There results a mental scale of general ability, adequate to gauge normality and to suggest practical standards of superiority or deficiency. The question at once arises: how far are the qualities desirable for this or that vocation of a general order, and how far are they specific in their demands. In this respect vocations differ widely. The musical vocation exemplifies a specialized profession depending upon a proficiency that is largely a dower of heredity; yet within this field the psychological test has proved its efficiency by determining the still more specialized facilities that jointly compose the psychology of the musician. In further pursuit of insight the psychological laboratory has undertaken to analyze the qualities needed for the several specialties of modern vocational life, by setting up "test" counterparts of practical occupations, by reducing them to their underlying facilities, by testing the correlation of quality and achievement, and by combining the clues or verdicts of several methods. Conclusions depend for their value upon logical caution and the technical methods which have been developed to meet these applications. All this is as yet but a program or a limited beginning in its execution; but it is a program well founded in principle and already in part available in practice.