MAT and GRE scores were equated by regression, conditional mean, linear and equipercentile methods using data from a sample that had taken both tests. The regression and linear methods were preferred, and shown to be equivalent when the correlation between scales is perfect. The choice between the two rests on the decision to include or not include the correlation in the equation. EDUCATIONAL AND PSYCHOLOGICAL MEASUREMENT 1980,40 THERE have been a number of studies regarding the relationship of the GRE and MAT, either separately or in combination, with subsequent academic performance (e.g., Felker, 1973;Krauskopf, 1973;Mehrabian, 1969;Nagi, 1975;Payne, Wells, and Clarke, 1971). Other studies have been done on retesting (Coldarci, 1960;Doppelt, 1971;Spielberger, 1959). There have been few, if any, studies on the relationship of these two scales, yet the question about comparative performance on one scale, given actual performance on the other scale has recurred sufficiently frequently that the authors were prompted to investigate this topic.One method of predicting, or equating, scores on one scale with probable scores on another scale has been by means of regression.Given means, standard deviations, and correlation on GRE and MAT scales for a sample of persons taking both tests, simple linear regression equations follow in a straightforward fashion. These take the form,