When William G. Perry (1968) developed his scheme of nine stages of cognitive development, most of which are experienced during the college years, he did not attempt to quantify it. Subsequently, T. D. Erwin (1983) constructed a scale that attempted to quantify the Perry scheme. His findings supported the overall conception of student development and supported the existence of three of the four superordinate stages suggested by Perry, as well as a less well-defined fourth factor. In this study, an attempt to quantify and validate the Perry scheme was made through an approach similar to Erwin's. A 45-item scale was developed and tested in 5 separate studies from 1983 to 1995. In all, 751 college students have responded to the scale. Factor analysis of the results from each of the separate studies has offered support for Perry's three superordinate stages: Dualism, Relativism, and Commitment. Findings, taken in conjunction with those of Erwin, provide evidence of the convergent validity of the Perry scale and support its temporal stability. An appendix presents the current scale version. (SLD)