The purpose of this descriptive case study was to describe elementary level school teachers' experiences who worked with English Learners in a project-based learning model of instruction. The study focused on how teachers developed, planned, or utilized curriculum to support the language acquisition of their English Learners to meet state and district mandates while maintaining the academic rigor inherent in a project-based learning environment. The bounded case of the study was the description of teachers' role in developing curriculum within a real-life context. A semistructured interview technique was used to garner the feelings and reflections of teachers experienced in meeting the multiple levels of academic needs English Learners may contend with while learning English and accessing grade level content. In addition, the study improved awareness in how project-based learning teachers of English Learners developed curricular units of instruction that provided authentic opportunities of learning while providing linguistic support through research-based instructional strategies. A constructivist theoretical framework guided the inquiry, and additional multiple corroborating sources such as teacher journals, classroom artifacts, field note observations, and archived documents were collected for data analysis. The data analysis occurred in two levels using Saldana's (2016) first and second cycle generic and affective coding processes. The coding analysis was informed by opportunity to learn standards that factored in teacher, school, district quality, content delivery methods, curriculum, resources, and facilities as a way to specify the potential to learn within a given space. Furthermore, tiered challenges is a term introduced in this study that captured the concept of how educational policies impacted teachers' professional development and either limited or supported their ability to meet the needs of their diverse English Language students in the classroom. Three educational themes emerged and were defined as a result of the study and revealed that mandates impacted English Learner student achievement, professional learning communities were significant components for English Learner student achievement, and teacher project-based knowledge influenced English Learner student achievement. [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.]