Social scientists are making increasing use of various indirect techniques of attitude assessment. These techniques, ranging from projective devices to hidden intelligence tests, are intended to elicit “deep-lying” attitudes or personality characteristics which might not otherwise be accessible to the investigator. In this article, the author argues that while these techniques may have considerable scientific value, their use and susceptibility to misuse raise serious problems of both an ethical and a practical character. Dr. Weschler suggests that the formulation of a code of procedure governing the use of such instruments may ultimately be necessary. This article is an expanded version of a paper presented to the annual convention of the American Psychological Association in September, 1950.