As the population of English language learners (ELLs) increases in public schools, teachers need additional training on ways to meet their educational needs. Teachers need to participate in sustainable, effective professional development that addresses the needs of ELLs who make up 10% of the public school population. The purpose of this study was to describe and interpret the experiences of teachers participating in professional learning communities (PLC) in 3 mid-sized, suburban elementary schools to determine the effectiveness of a PLC in developing skills for instructing ELLs. DuFour, DuFour, and Eaker's theoretical framework for a PLC was used as the model. This qualitative case study examined how participating in a PLC served as a resource for developing instructional practices for teachers of ELLs. Three focus group and 5 individual interviews were used to gather qualitative data. An inductive analysis model was used to analyze the data and identify 17 themes. Findings suggest that PLCs are more effective than traditional professional development because they are (a) ongoing and connected to the specific needs of the population at each individual school and (b) provide a viable means for internal professional development, capitalizing on the skills, strengths, and varied backgrounds of teachers at each school site. The outcome of this study was a professional development model that supports schools in implementing sustainable PLCs to improve instructional strategies for teachers of ELLs. This model can provide a better educational opportunity for ELLs by promoting collective action among school staff and thus improve the academic achievement of ELLs. [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.]