In a three-year study, RAND researchers examined the relationship between reform-oriented instruction and student performance in mathematics and science. At the end of the study, students who had been exposed to more reform-oriented teaching performed better in both math and science than those who had experienced less, but the differences in scores were small. The relationship between instructional practice and student performance was stronger when performance was measured on items that required problem-solving skills rather than procedural skills, an outcome that is generally consistent with the goals of reform-oriented teaching. These results illustrate the importance of matching performance measures to reform goals in evaluating instructional innovations. (Contains 1 footnote.) [This research brief describes work documented in "Improving Mathematics and Science Education: A Longitudinal Investigation of the Relationship Between Reform-Oriented Instruction and Student Achievement," by Vi-Nhuan Le, Brian M. Stecher, J. R. Lockwood, Laura S. Hamilton, Abby Robyn, Valerie L. Williams, Gery Ryan, Kerri A. Kerr, Jose Felipe Martinez, and Stephen P. Klein. See ED494015.]