Credence in the notion that lower Negro performance on IQ tests results from teachers' expectations was widely promulgated by one of the most hig'hly publicized studies in the recent history of educational researc:h - the famous Pygmalion in the Classroom study by Rosenthal and Jacobson (1968). The main thesis of these authors is that a teacher's expectation of what pupils are able to do creates a 'self-fulfilling prophecy' which actually raises or lowers the childrell's IQs and level of scholastic achievements. Thus, initial differ(;~nces in test scores, if known to the teachers, should become magnified in subsequent testings as a result of teacher expectations. And similarly, on the basis of previous experience, preconeeptions, etc. concerning the relative abilities of Negro and white children, teachers' expectations should, according to this hypothesis, create or magnify performance differences between Negro and white pupils.