The work of mathematics education often seeks to increase student success, but rarely explicitly defines this concept. When it is, it commonly corresponds with quantitative measures that enable the positioning of students as economic resources within a school or university's institutional structure, providing an incomplete portrait of student success and reinforcing deficit perspectives on student achievement. Fostering critical analysis of how we conceptualize student success within mathematics requires aligning how we define such success with the perspectives of mathematics students. I advocate for centering student voice in the (re)defining of student success, and issue a call to the mathematics education community to (1) make definitions of student success explicit in mathematics education research and policy, and (2) acknowledge and value the expansive nature of students' definitions of their own mathematical success. [For the complete proceedings, see ED630060.]