["Journal of Research on Adolescence, Volume 36, Issue 2, June 2026. ", "\nAbstract\nThis study examines how critical participatory action research (cPAR) can advance education measurement development by positioning Black and Latino students and their teachers as co‐researchers. As part of the Adapted Measure of Math Engagement (AM‐ME) Project, a three‐year partnership with a school district in the Midwestern region of the U.S., students, teachers, and academic researchers collaboratively defined math engagement, co‐created survey items, analyzed qualitative evidence, and developed practice recommendations. Drawing on reflections, artifacts, and action‐planning products from the AM‐ME Research Group, findings show that participation fostered new researcher identities for students and teachers, strengthened cultural responsiveness and methodological rigor, and generated actionable classroom and district strategies. The project highlights how embedding cPAR into measurement development may produce more credible and culturally grounded instruments and cultivate youth and teacher agency while directly informing educational practice. These results highlight the potential of participatory methodologies to bridge research and practice and to expand how developmental and educational sciences conceptualize student engagement.\n"]