When four forces create shift in the landscape of PK-12 education, change in response to the environment is inevitable and necessary. It is such in the United States, as schools face increased accountability for the growth and attainment of reading skills, rigorous demands of the Common Core State Standards, a rapidly growing population of students for whom English is not their primary language, and a workforce of teachers who have had little training on how to address the needs of diverse learners. Since teacher efficacy is considered one of the greatest factors in student success, it stands to reason that professional development in strategies with the greatest potential impact on student achievement would be of primary importance in driving that response. SIOP (Sheltered Instruction Observation Protocol) is a framework of strategies that holds promise as having that desired impact. Each of the SIOP strategies themselves is based in research, and is utilized specifically for the purpose of making academic language more accessible for students whose primary language is not English. In this study, the reading achievement of students in grades one and two, measured by growth on the Measure of Academic Progress (MAP) assessment, and the reading portion of the WIDA-ACCESS (World-Class Instructional Design and Assessment-Assessing Comprehension and Communication in English State to State), was examined before and after exposure to instruction from a teacher who was trained in, and was implementing, the SIOP framework. The data collected in this research study came from over 2500 students in the first through second grade classrooms of one hundred-one general education teachers, and twenty-one transitional bilingual education teachers from a large suburban school district in the Midwest. The data collected spanned a one year period of time, and noted a positive, but not completely conclusive result. [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.]