When professional learning communities (PLCs) are developed to promote the academic achievement of English language learners (ELLs), the results can benefit not only ELLs but the whole school. This article examines the ventures of three high schools that implemented PLCs as part of a Title III National Professional Development Project. The authors highlight the research on the effectiveness of PLCs and offer an operational definition for envisioning PLCs. Case studies of the three high school teams illustrate different cycles of inquiry and help readers understand how the emergence and development of professional teams improve the instruction and learning of ELLs. Using principles of effective PLCs as a framework, the authors share the challenges and successes of each team. The article concludes that effective PLCs are focused by a commitment to improve learning, informed by recognized principles, structured by the norms and inquiry processes that team members establish, and guided by school leaders who support teams and help them envision goals worth pursuing. (Contains 8 footnotes.)