The purpose of this study was to determine the existence of a relationship between online professional development and English language arts (ELA) teachers' instructional practices. Professional development is commonly utilized to develop teachers' pedagogy, but in-person sessions do not meet all teachers' needs. "Mixed methods" research was utilized to examine relationships between teachers' ability to create and incorporate assignments based on levels 3 or 4 of Webb's Depth of Knowledge (DOK) Framework, self-efficacy regarding teaching higher-order thinking skills, and online professional development on those topics. The results indicated a moderate, positive directional relationship between these components. The only statistically significant relationship existed between teachers' incorporation of tasks from Webb's DOK levels 3 or 4 and their online professional development performance. [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.]