Many African American students have different learning styles than their Caucasian and Asian American counterparts. This distinction makes differentiated instruction a vital teaching strategy, as it allows teachers to tailor curriculum and teaching to meet the needs of individual students, especially those with different learning styles. This quasi-experimental case study design sought to determine the effectiveness of differentiated instruction on African Americans' Algebra I End-of-Course exam scores. The theoretical framework of this study was based on constructivism the work of Piaget and Vygotsky. The research questions were used to discover if a connection exists between pre- and post-exam scores within a select group of African American students, analyzing the impact of direct instruction verses differentiated instruction on standardized test outcomes. A sample of 120 9th grade African American high school students in a North Carolina school district was used for this study. An independent samples t-test was conducted to compare mathematical achievement for students receiving direct and differentiated instruction, and showed a significant positive difference in the mean math score for those students receiving differentiated instruction. These findings highlight the need for enhanced instructional strategy for African American students so as to increase skills and learning. Implications for positive social change include increased cultural awareness among teachers in their instructional methods. This awareness of cultural diversity will provide African American students with the essential knowledge and skills needed to become more confident and self-sufficient students. Furthermore, teachers' continued awareness of the positive impact of differentiated instruction will provide an impetus to address the needs of all learners. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]