"Fraction Face-Off!" is a supplemental math program designed to support fourth-grade students who need assistance solving fraction problems. Teachers use program materials with individual students or small groups to promote understanding of the magnitude of fractions, to compare two fractions, to put three fractions in order, and to place fractions on a number line. The program includes 36 lessons, each with four activities: a warm-up problem, group work, a speed game to build fluency, and a worksheet to check students' understanding. These lessons are designed to be taught three times a week for 12 weeks. This What Works Clearinghouse (WWC) report, part of the WWC's Primary Mathematics topic area, explores the effects of "Fraction Face-Off!" on mathematics outcome domains including geometry and measurement, number and operations, and general mathematics achievement. The WWC identified one study of "Fraction Face-Off!," which meets WWC standards. The evidence presented in this report is from one study of the impact of "Fraction Face-Off!" on a racially and ethnically diverse group of fourth-grade students. [For the full report, see ED603593. For the Intervention Snapshot, see ED603592.]