This study focused on the continued mathematical achievement gap between African American and Latino students in an urban elementary school. An illustrative case study design was used to examine the teachers' perception of factors contributing to this gap in mathematical performance, and what instructional math strategies can narrow the achievement gap. Socioconstructivism and culturally relevant pedagogy were the learning theories used to form the conceptual framework in this study. Qualitative data were obtained from 6 individual interviews with 4th grade math educators, classroom observations, and teacher artifacts. Data analysis in this study included data triangulation and coding, as well as identification of common themes as an important analytical approach to enhance the credibility of this study. Methods for minimizing bias and error included peer debriefing and member-checking, which consisted of obtaining feedback from participants to ensure the trustworthiness of findings. The key results of this study indicated that teachers perceived that 4th grade African American students often lacked basic skills and background knowledge for their school grade. Based upon the findings, the outcome was a plan for professional development training to help teachers gain knowledge on how to incorporate cultural relevant pedagogy, through strategies that include differentiating learning instructions and mastery learning into their classrooms, to narrow the mathematical achievement gap between African American and Latino 4th grade students. Implications for positive social change from this study include providing teachers with research-based strategies targeted toward narrowing the mathematical achievement gap between 4th grade African American and Latino students at the local and district site.