The lack of empirical scholarship on professional development initiatives for teachers of English language learners (ELLs) in US schools has been repeatedly documented in educational research. The present dissertation project examines a professional development course specifically designed for K-12 teachers of ELLs. The course aims to foster the development of a professional learning community and provide educators with practical tools for the instruction of ELLs. The researcher uses ethnographic methods and a type of discourse analysis (microethnography) to investigate the factors that affect the sustainability and nature of that community, and the teacher learning that occurs. The data collected include field notes, recordings of face-to-face sessions, online discussions, course documents, course assignments, interviews with participants, and surveys. The researcher uses systems theory as developed by Niklas Luhmann to explain and extend the findings of the ethnographic microanalysis. She explores the learning context of the professional development course through an analysis of discursive norms and describes some of the types of learning that take place during the course. In addition, the researcher investigates the extent to which the learning environment in the professional development course represents a professional learning community and discusses the relevance of the term community to empirical investigations of K-12 professional development. Through a detailed empirical analysis of the interaction among stakeholders with diverse knowledge of and experience with ELLs (including course facilitators, school administrators, district administrators, mainstream teachers, specialists, and observers), the project sheds light on a phenomenon that is currently little understood: the professional learning of teachers of ELLs that has the potential to positively affect their practice. [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.]