This dissertation examined how adult learners who took developmental mathematics in a community college and passed the courses, viewed their self-efficacy and the roles they felt self-efficacy had on their successful completion of mathematics. Semi-structured interviews were conducted with 10 adult learners in two U.S. community colleges. Transcripts were analyzed using Interpretative Phenomenological Analysis (IPA) to identify themes. Three major themes emerged: positive math class interaction that entailed regular class attendance; asking questions about mathematics, practicing developmental mathematics skills, using supplemental resources to strengthen mathematical skills, and prior mathematics success; positive personal attributes that students discussed such as personal discipline, desire to learn, and personal motivation; and support from family members and non-family members. These findings took into account the literature on developmental mathematics and considered Bandura's (1997) self-efficacy theoretical framework. [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.]