A simulation study was designed to assess the severity of regression effects when a set of selection scores is also used as pretest scores as this pertains to RMC Model A of the Elementary and Secondary Education Act Title I evaluation and reporting system. Data sets were created with various characteristics (varying data reliability and extremeness of subgroups) that are relevant to the regression phenomenon. These data sets were analyzed to obtain indices of the amount of regression which might occur under various conditions. An adjustment method was presented which predicted pretest scores on the basis of selection scores and the correlation between selection and pretest, the correlation coefficient being replaceable by such indices of reliability as the internal consistency coefficient. Results suggest that when data reliability is high (.94 or above) the impact of regression effects appears small; but when reliability is low the effects of regression are hard to predict. When selection test scores are of high reliability, such regressed scores may be used as a pretest measure without severely biasing the evaluation results. Results can be used to formulate a rule-of-thumb for adjusting selection scores when they are to be used as pretest scores also. (Author/CP)