Public schools are attempting to work with a growing number of immigrant English language learners (ELLs) in the U.S. education system at a time when the No Child Left Behind (NCLB) Act has mandated that ELLs achieve proficiency on assessments even if they have not acquired sufficient language proficiency. The purpose of this qualitative case study at a Midwestern elementary school was to investigate support staff, teacher, and administrator perceptions of the assessment accommodation process for ELLs about high-stakes testing. The conceptual framework for the study was based on second language acquisition (SLA) and basic interpersonal communication skills and cognitive academic language proficiency. Research questions guided the investigation regarding the development of the Student Language Assessment Plan (SLAP) and the perceptions of teachers regarding the SLAP process. Data were collected through observations of the SLAP process in assessed grade level data meetings, interviews with 5 teachers, and review of SLAP documents. Open, axial, and selective coding was used to identify themes and categories within the data. Results showed that the participants lacked knowledge about the SLAP and would benefit from targeted professional development (PD) with more utilization of formal assessment measures for the SLAP. A PD Project involved the collaboration of school staff, parents, and community members and was designed to increase their knowledge of SLA while promoting the academic advancement of ELLs. Implications for positive social change from the PD Project presented an opportunity to directly impact the school staff, parents, and community members while indirectly impacting ELLs and students' lives. [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.]