While implementation efforts using a Response to Intervention (RtI) model to increase reading instruction are becoming widely used, more administrators and teachers are looking to learn effective RtI practices to support learning in mathematics. This article explores some of the key elements of RtI practices in mathematics, including screening for identification of struggling learners and progress monitoring for gauging instructional effectiveness. In addition, several of the pressing needs regarding the importance of mathematics proficiency for all students are discussed. We describe some of the similarities and differences between RtI processes in reading and mathematics. The article addresses the use of diagnostic data and details the importance of "core" instructional practices that reflect the standards included in the National Council of Teachers of Mathematics standards and Common Core Mathematics standards, among others. The article concludes with a discussion of some evidence-based interventions in mathematics, and we provide an implementation checklist to assist educators as they begin to implement RtI in mathematics. (Contains 3 tables.)