This study was mounted to assess the validity of standard score transformations of raw test scores and test bias on the 1970 edition of the Metropolitan Achievement Test Battery, in the context of a controversial federally funded compensatory education program, the Educational Voucher Demonstration (EVD). On an individual level the validity of the Standard Score scale has not been demonstrated. Moreover, substantial bias was found in aggregate measures (means and medians) between adjacent difficulty levels. For these reasons, the authors could not conclude with any confidence that the instrument herein assessed could provide dependable bases either for individual student assessment, or program evaluation as usually performed. (MV)