Large numbers of students are not proficient in mathematics and there are disparities in mathematics achievement between students from different ethnic and socioeconomic groups. Mathematics skills are important for both academic and workplace success and there are a large number of interventions that aim to improve student mathematics achievement. This review focuses on mathematics interventions that are typically used in kindergarten through grade 8 and are designed to affect students' mathematics achievement. This protocol guides the review of research that informs the What Works Clearinghouse (WWC) Primary Mathematics (PM) intervention reports. The protocol is used in conjunction with the "WWC Procedures and Standards Handbooks (version 4.0)."