The Myers-Briggs T~rpe Indicator is a self-report inventory which is intended to measure four variables stemming from the Jungian personality typology: extraversion-introversion, sensati.on-intuition, thinking-feeling, andjudging-perceivlng v The construct validity of each of its scales was assessed in a series of studies which investigated the content of the scales, their correlations with ability, interest, and personality scales, and differences on the (Jung, 1923;Jung, 1933;Jung, 1953) . has been widely influential., i·ts main impact on personality measurement has been to promote an abiding interest in just one facet of the typology--extraversion-introversion. The many scales which have been d.eveloped through the years to measure this variable attest to the intensity of this interest.The measurement of the other variables in Jungls typology, hovrever, has not been entirely neglected. Some time ago, the Gray-'\'lheehrright Psychological. T)~e Questionnaire (Gray, 1947;Gray, 1948;Gray, 1949; Gray & Wheelwright, 1946) was developed to measure all the variables in Jw~'s typology--the attitudes (extraversion and introversion) as well as the functions (sensation, intuition, thinking, and feeling). More recently, there has been gro\,ring interest in a similar inventory, the Myers-Briggs Type Indicator (rvlyers, 1962b). In vie"T of the increasing use of the Indicator (e.g., Child, 1962;Howarth, 1962;Laney, 1949;Lord, 1958; MacKilli"lOn, 1962; Myers, 1962a; Myers, 1962b;Ross, 1961;Saunders, 1957;Saunders, 1960; Smucker, 1959;Taylor, 1960;von Fange, 1961) and its potential relevance in operationally defining Jungls typology, an assessment of the construct valid.:i.'ty of its scales seems appropriate. A start in this d.irection has been made (HoY(iarth, 1962; trers, 1962b;Saunders, 1960). This article is based upon the results of a series of studies which bear on t'i-TO related issues: (a) Y(Thether the Indicator scales appropriately reflect the distinctions embodied in the typology and exPlicitly described in the conceptual definition of each of the typological variablesj and, alternatively, (b) whether the Indicator scales reflect, to a greater or lesser extent, other variables '1.;rhich are -2-not a part of the typology. The first of these studies, focussing on the internal properties of the scales, employed an item analysis of the scales' content to identify those items which best typify the scales.The other studies examined the scales' links to external variables by investigatir~the scales' correlations with ability, interest, and personality scales, and differences on the scales between males and females, and bet'treen high school students in college preparatory and generalvocational programs.