Online professional development (OPD) is a recent innovation in K-12 school districts. While many studies have examined the skills and competencies of online instructors few studies have examined online learning for adults through the perspective of instructor beliefs. This qualitative case study examined the beliefs of five OPD instructors about online learning for adults, online learning environments, and instructional strategies to facilitate learning. Findings from this study have implications for online instructors, adult learners, and for OPD programs in school districts and academic settings. This book would be useful for scholars and practitioners interested in online teaching and learning in K-12 and academic settings.