The increasing use of educational performance or outcome measurements for a range of policy purposes points to new procedures for adjusting data for population composition. The purposes include: program formulation, budget resource allocation, grant-in-aid designs, performance incentive payments, consumer information for school selection, and program evaluation and review. This paper outlines methods for controlling population differences to make data on performance more comparable across time and from place to place. The resulting estimates of achievement scores, standardized for population differences, are useful for comparison only. Such comparative indexes remove the influence on average scores of population changes over time, or population differences between schools or school districts. Adjusted scores are not intended to take the place of the basic data but to complement them. Standardization procedures can be applied to achievement test scores and to other measurements of competence such as attitudes or attributes. In this report, achievement score adjustment is used as an example. The selection of sex, income, and race (SIR) as control variables is proposed as a first step. (Author/SE)