This chapter summarizes theoretical perspectives, pedagogical practices and recommendations for advancement in using sign language to teach mathematics to Deaf learners who are native users of sign language. The literature demonstrates that using a signed language as a language of instruction supports the learning of mathematical concepts for Deaf children in both L1 and L2/Ln. Deaf learners of widely varied backgrounds demonstrate mathematics performance gains that bring them in line with hearing peers only after two years in a well-designed bilingual program. Learners, researchers, and deaf educational professionals recognize that teachers’ and classroom interpreters’ sign language abilities, along with academic content knowledge, are crucial to learner learning. The chapter presents considerations of sign language in the mathematical pedagogy areas of curriculum, instruction, and assessment.