Like many universities nationwide, a substantial number of students at Wilmington University (WU) who are placed into remedial mathematics courses do not pass these courses, and consequently, do not earn degrees. The literature on remedial college courses indicates that instruction is one factor that contributes to the challenges students experience in these courses. Wilmington University is a four-year university primarily located in New Castle, Delaware, serving a population of approximately 20,000 students. This Education Leadership Portfolio documents my efforts to address two problems associated with remedial mathematics courses at WU: teaching methods that do not provide sufficient opportunities for students to develop conceptual understanding and low pass rates for students enrolled in these courses. My goals were to increase instructors' use of teaching methods that promote active learning (AL) and to increase students' understanding of course content. To accomplish these goals, I created and implemented professional development (PD) that supported the use of AL-oriented teaching methods in a remedial mathematics course. I focused on three aspects of teaching that supports AL: classroom culture, meaningful tasks, and student collaboration. I examined the efficacy of the PD by analyzing instructor interview transcripts, student survey results, and student achievement data. Four instructors voluntarily participated in the PD and 66 students elected to enroll in sections of the remedial mathematics course; students were not assigned to sections. Results indicate that instructors improved in their understanding and use of meaningful tasks, but not the other aspects. Results also indicated the importance of addressing instructors' beliefs about teaching. Students perceived their instructors incorporated all AL-oriented teaching methods and all of these methods were helpful to learning course content. Furthermore, only students taught by instructors who participated in the PD showed growth between the pre-test and post-test about course concepts. Collectively, these results indicate that PD may be a promising strategy to improve the content understanding of students enrolled in remedial mathematics courses. However, this study is limited by a small sample size and the inability to disaggregate student survey data to individual instructors. Based on these findings, opportunities exist to improve PD implementation by focusing on instructors' pre-existing beliefs about teaching and to improve methodology by redesigning the student survey and revising the attendance policy. I recommended that this study be replicated once student enrollment increases. Professional development meetings should be offered weekly, rather than monthly, in order to address instructors' beliefs about effective pedagogy. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]