Out-of-school time (OST) science, technology, engineering, and math (STEM) programs have gained recognition for their potential to enhance youth engagement, motivation, and skills by addressing young people's needs for autonomy, competence, and connection (Faust & Kuperminc, 2020; Hoffman et al., 2021; Mulvey et al., 2023; Yu et al., 2022; Yu et al., 2020). These programs, particularly when they combine academic and social focuses, can significantly impact student interest in STEM, with middle school being an optimal stage for intervention (Young, Ortiz, & Young, 2017). OST activities have the potential to address the opportunity gap faced by underserved communities in STEM. However, creating truly inclusive environments requires the adoption of culturally responsive practices (Simpkins et al., 2017). This article presents a case study on enhancing cultural responsiveness in an afterschool STEM program serving marginalized youth from groups that are underrepresented in STEM. The program fosters both academic and social growth through a framework called the Math CEO CRT framework, which consists of six key dimensions. Each dimension is detailed with pedagogical practices, implementation examples, and potential impacts on students. By examining the integration of these dimensions into the program's curriculum, staff-youth interactions, and program structure, this study offers valuable insights to inform future STEM program design and practical implementation strategies.