The purpose of this study was to determine which academic and affective student factors were significant to student success in a mastery learning program in developmental mathematics and to determine if the mastery learning program led to increased mathematical knowledge retention and success in the subsequent math course. The first phase of the study involved 298 students in developmental mathematics. Using binary logistic regression, the researcher found that placement test score, previous experience with mastery learning, and gender were statistically significant factors related to student success in the mastery learning program. The second phase of the study involved 529 students in the subsequent course intermediate algebra. Using one-way analysis of variance and chi-square methods, the researcher found that mastery learning students retained significantly more mathematical content knowledge and succeeded at significantly higher rates in the subsequent course intermediate algebra as compared to students who took developmental mathematics through traditional methods and those who opted out of placement testing. Results of the study showed that the mastery learning approach in developmental mathematics which incorporated the affective student domain offered advantages for assisting students to overcome math background and self-efficacy barriers. [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.]