Teacher shortages and lack of teacher diversity have led to growing efforts nationally to recruit teaching assistants (TAs) to be classroom teachers. Substitute teachers are not typically considered in these efforts. We pair longitudinal administrative data from a mid-sized urban district with survey follow-up to address how TAs and substitute teachers contribute to filling staffing shortages and diversifying the teacher workforce. While substitute teachers are rarely included in formal Grow-Your-Own efforts, they bring racial and ethnic diversity to the district in similar ways to TAs yet face fewer barriers to becoming classroom teachers. As a result, they do so at much higher rates and help prevent vacancies in hard-to-staff classrooms.