High school classroom teachers with English language learners (ELLs) assigned to their classrooms might not be using effective instructional strategies to increase reading comprehension scores of ELLs. The purpose of this basic qualitative study was to explore the use of strategies that high school classroom teachers use to teach cognitive academic language proficiency (CALP) to ELLs who have difficulty reading for understanding. The conceptual framework guiding this study was Cummin's second language acquisition theory. The basic qualitative research design was guided by two research questions intended to determine the effectiveness of strategies used by the high school classroom teachers to help ELLs learn CALP for improving reading comprehension. A basic qualitative study using open-ended, semistructured interviews with 13 general education teachers was used in this study to determine if teachers are using strategies to help their ELLs learn CALP. The inclusion criteria for the study were general education high school teachers who were not certified to teach ELLs but were providing instruction to ELLs. Interview responses were analyzed using NVivo 12 and content analysis to determine trends and patterns in the data. Coding included inductive coding to develop categories that could be combined into themes that could be used to address the research questions. School administrators might use the results of this study to plan professional development programs for general education teachers who are working with ELLs in their classrooms. Understanding effective strategies that teachers use can help ELLs learn CALP and students achieve their academic goals. The social change that this research might accomplish is providing teachers with the tools that could help their ELL students become college or career ready and be successful citizens in an increasingly global economy. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]