National educational assessment organizations present statistical information that an achievement gap exists between White students and students of color. This achievement gap closely relates to students representing lower SES conditions. This study examined the lack of achievement for ethnic minorities in the field of mathematics using an experimental methods design. A classroom intervention using differentiated instruction (DI) based on learning styles theory was implemented with minority students deficient in mathematics skills. First-year college students enrolled in developmental mathematics courses were the population of interest. Additionally, the primary ethnic groups enrolled at the college under study were African American and Hispanic. Collaborative learning was incorporated to contribute to achievement in mathematics. The hypotheses involved mathematics self-efficacy and learning styles representing major variables in the attainment of mathematics achievement and performance. Other data collection tools were portfolio construction and mathematical analysis for observing students' learning. Student engagement was measured and assessed with a passing score by this College's learning center before advancing on to the next grade. The results showed that African Americans can excel in mathematics when DI is used. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]