AbstractState frameworks and national standards are explicit about the mathematics content that students must master at each grade level. Although the Individuals with Disabilities Education Act and the No Child Left Behind Act mandate that students who are deaf or hard of hearing and communicate in sign language have access to this content, evidence suggests that it remains out of reach for many in this group. The purpose of the implementation research described in this article was to examine use of a Signing Math Dictionary (SMD) to help students who are members of this population access the vocabulary required to master the mathematics content that underlies the topics they are studying. The study included eight separate classes and a total of 39 participants—8 teachers and 31 students—representing grades 4–8. The research design incorporated a descriptive case study methodology that involved observing (a) teaching mathematics without the SMD, (b) preparing students to use the SMD, (c) teaching mathema...