Curriculum-based measurement (CBM) is described as a method of helping teachers measure student performance accurately and adapt their instruction to improve student achievement. Curriculum-based measurement's features include measurement of student proficiency across the annual curriculum, and use of a standardized, prescriptive measurement methodology with demonstrated psychometric acceptability. Curriculum-based measurement is contrasted with the more predominant form of measurement known as mastery measurement. The use of CBM to develop effective instructional programs and to monitor and adjust goals is described. A study which evaluated the use of CBM with and without an expert consultation system in math operations is reported, with the finding that the instructional changes made by those teachers in the CBM group with expert consultation were superior in quality and variety to those made by the group without such consultation. Current research directions are also described, and a list of nine related readings is appended. (JDD)