Scores on state-mandated assessments indicate English Language Learner students (ELLs) at Happy Town High School (HTHS) are not performing as well as their non-ELL peers. During the 2014-18 school years, the ELL population failed to meet expectations in most of their end-of-course exams. In response, administrators have focused their efforts on creating and providing teachers additional tools to support the ELLs' instructional needs and academic development. To that end, teachers receive professional development training each year, which provides research-based, best practice instructional strategies. Despite the targeted professional development provided to teachers, current ELLs' academic assessment scores have not improved significantly. This research study attempts to use a more focused field-based approach to professional development of the teachers on this issue by focusing on the coaching, monitoring, and implementation of the sheltered instructional strategies that teachers learned in district-provided professional development to support English Language Learners. Two questionnaires adapted which incorporate sheltered instructional strategies were used to collect the data on sheltered instructional strategies to be analyzed in this study. A mixed method approach was used to examine the data in this study. The results show there was no significant improvement in any of the components of planning and daily instruction. However, the coached group improved in providing comprehensible input to the students and performed better than the non-coached group in the lesson. The findings of this study can inform the district and school administrators in the implementation of sheltered instructional strategies and in how to support teachers' professional development in order to facilitate the learning of ELL students. The professional development model used in this study indicates that ongoing instructional coaching and support is needed for all teachers to facilitate the implementation of appropriate sheltered instruction strategies in the classroom. [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.]