Adjunct faculty teach over 50% of courses in U.S. higher education but little is known about them as educators. Strong evidence has been found in the K-12 literature demonstrating the link between teachers' beliefs, instructional practices, and subsequent student outcomes. Teaching self-efficacy, beliefs in one's capabilities to perform specific tasks in a particular context, is an important contributor to motivation and performance (Tschannen-Moran et al., 1998). This research advances teaching and learning literature in higher education and provides insight into an understudied population of educators by exploring adjunct faculty's teaching self-efficacy and factors that influence those beliefs. In this mixed methods study, an explanatory sequential design was used to explore teaching-self efficacy among adjunct faculty at a Mid-Atlantic community college. Adjunct faculty were surveyed using the College Teaching Self-Efficacy Scale (Prieto Navarro, 2006). Data were selected from the surveys for further explanation in subsequent interviews. Quantitative and qualitative data were merged to form an overall interpretation of teaching self-efficacy and factors that influenced those beliefs. Teaching self-efficacy was highest in creating a positive learning environment, followed by overall teaching self-efficacy, and then instructional skills. Assessing student learning was rated lowest. Adjunct faculty with fewer than five years teaching experience had lower self-efficacy scores than those teaching for six or more years. Mastery experiences and feedback from students and full-time faculty mentors emerged as the most influential sources of teaching self-efficacy. Student evaluations and attending Convocation were positively correlated with scores in overall teaching self-efficacy, instructional skills, and creating a positive learning environment. Adjunct faculty identified working to accommodate the needs of a diverse range of learners as the most significant challenge to teaching self-efficacy followed by challenges related to working conditions including inadequate pay and job insecurity. Key recommendations for promoting adjunct faculty's teaching self-efficacy beliefs include increasing opportunities for interaction with departmental colleagues to share best practices and teaching resources, and offering trainings at flexible times and in creative formats on instructional skills, assessment practices, and learning theories. Improving onboarding processes, recognizing different needs of adjunct faculty based on experience, and reassessing pay and employment structures are also needed. [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.]