<p>This article examines a collaborative student research project co-designed and facilitated by a mathematics teacher and an American Sign Language (ASL) teacher across two courses, Statistics and ASL III/IV, at a small private high school in California serving predominantly students with learning differences. This article explores the possibilities and tensions of the Statistics and ASL Disability Rights project as a case of transdisciplinary design for equity in mathematics education. We define equity in relation to opportunities for youth to develop as historical actors (K. Gutiérrez et al.2019) and articulate such possibilities in relation to the ways youth used mathematical practices alongside disability justice principles (Berne, 2015) throughout the project. Through this illuminating case of transdisciplinary design in mathematics education, we highlight possibilities for equity that center identity, agency, and power not only in the mathematics students learn, but in the people that students become. Finally, we articulate implications for equitable mathematics in relation to teacher collaboration and transdisciplinary design, connecting curriculum to youth interests, and identifying locations for youth voice.</p>