Proficiency in reading is an essential skill for achieving success in the modern era, and African American students have struggled with reading due to insufficient support during literacy instruction. Through the implementation of the Science of Reading™ course, this research aimed to examine the effect of the Language Essentials for Teachers of Reading and Spelling (LETRS™) curriculum on the success of African American third-grade males based on the South Carolina College- and Career-Ready (SC READY™) summative assessments and Northwest Academic Evaluation Measures of Academic Progress (NWEA MAP™) data. This study followed the year before LETRS™ was introduced (2019), the 2 years of training (2021 and 2022), and the year after the teachers completed the training (2023). Piaget's (1964) cognitive development theory explains the steps and paths children go through as they learn to think and reason. As an important part of teaching reading, the schema theory also supported this study by explaining how well someone understands the world through comprehension. This quantitative study suggests that the LETRS™ professional development course and Science of Reading™ practices did not show an immediate impact on student performance scores, but they showed statistical significance over time as indicated by SC READY™ summative assessments in 2023; hence, it may be inferred that LETRS™ has a favorable effect on teacher knowledge and student accomplishment. There was no statistical significance found on the NWEA MAP™ tests due to the test being adaptable. [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.]