This review examined a study designed to evaluate whether the Achievement Challenge Pilot Project, a performance-pay program for teachers, improved the academic achievement of elementary school students. Study authors reported higher student test score gains for students in schools that implemented the performance- pay program than for students in schools without the program. The review reports that the research described in the study is not consistent with What Works Clearinghouse (WWC) evidence standards. The study compared student test score gains in the three schools that implemented the performance-pay program in 2006-07 with test score gains in district schools that did not implement the program. Because the program was targeted to low-performing schools with high proportions of low-income students, the two groups of schools initially had very different student characteristics and average test scores. Although the study authors control for some of these differences in their analysis, there may be other differences between the schools that could influence student test score gains. In addition, the lowest-performing schools may have implemented other changes to improve test scores in an attempt to meet statewide accountability standards and these other changes may have influenced test score gains. For these reasons, differences in test score gains cannot be attributed with confidence to the effect of the performance-pay program. [The following report was the focus of this "Quick Review": "The Effect of Performance-Pay in Little Rock, Arkansas on Student Achievement." Working Paper 2008-02. Marcus Winters, Jay P. Greene, Gary Ritter, and Ryan Marsh. National Center on Performance Incentives. January 2008.]