Problem Statement: As a result of the COVID-19 pandemic, students were negatively impacted academically and social-emotionally (Kuhfeld et al., 2020). Preexisting academic inequities were exacerbated, especially for students of color, students with disabilities, multilingual learners, and those from low-income backgrounds (Kuhfeld et al., 2022). To address these issues schools, developed programs using American Rescue Plan Funds to accelerate learning by offering intensive, targeted instruction in summer programs (Harris et al., 2021). Arguably, one of the most important skills to ensure that students receive high-quality instruction is reading. When children and adults can read the written word, they can gain new skills, discover interests, and build knowledge (Ehri, 2022; Kirsch et al., 2002; Murnane et al., 2012; Snow et al., 1998). Although reading is an integral life skill, only 35% of fourth-grade public school students scored at or above proficiency in reading on the 2019 National Assessment of Educational Progress (NAEP) (National Center for Education Statistics -NCES, 2019a). As a result of the pandemic, these numbers worsened, with average reading scores for students declining 5 points from 2020 to 2022, the largest drop in reading since 1990 (NCES, 2022). For children to become proficient readers, it is imperative that students acquire strong early literacy foundational skills (Goldstein et al., 2016). Foster and Miller (2007) found that kindergarten students who did not perform as well as their peers in literacy later struggled with comprehension skills during third grade. Although most schools in the United States use a core comprehensive curriculum, students continue to perform poorly on national reading assessments (Dewitz & Sullivan, 2010). To accelerate student learning, early elementary teachers and students could benefit from a systematic and explicit supplemental text-based, phonics and word study program that focuses on building strong phonological awareness skills, phonics skills, and word study skills (Castles et al., 2018; Liben & Page, 2017). These skills should be taught while supporting comprehension skill development and knowledge building (Cervetti & Hievert, 2019; Ehri, 2020; Spear-Swerling, 2019). Methodology: A single-subject, quasi-experimental quantitative study was used to evaluate the effectiveness of a supplemental early literacy program on kindergarten through third-grade students (N = 85) in an urban city in the state of Alabama during a four-week summer school intensive program. To assess the impact of the program, the researcher analyzed pretest and posttest data from the Dynamic Indicators of Basic Early Literacy Skills (DIBELS) assessment for kindergarten through third-grade students during the 2022 summer program after receiving the treatment. The researcher also analyzed pretest and posttest data from the spring 2022 and summer 2022 administration of the Alabama Comprehensive Assessment Program (ACAP) Summative Reading Subset test for third-grade students after treatment. Using pretest and posttest data, the researcher answered the following research questions: Research Question 1: What is the effect of the supplemental phonics program on DIBELS composite reading scores when comparing the spring DIBELS composite scores in May 2022 to the DIBELS composite score administered at the end of the summer program in June 2022? Research Question 2: What is the effect of the supplemental phonics program on third-grade students' Alabama ACAP reading scores from the administration in May 2022 compared to the state test administered at the end of the summer program in June 2022? Research Question 3: What is the effect of the supplement phonics program on DIBELS composite reading scores based on student demographics, specifically for gender, race/ethnicity, special education status, English language proficiency, and free or reduced lunch eligibility? Findings: The results of this study suggest that the supplemental program is effective in supporting struggling kindergarten through third-grade students with early literacy skills and helps to improve students' reading proficiency. Specifically, the data showed an increase in average mean reading scores from the spring DIBELS pretest to the summer DIBELS posttest. All grade levels made gains from pretest to posttest, but only students in kindergarten, first grade, and third grade had an average mean increase that indicated an improvement from the level of at-risk to the level of some risk. In addition, third-grade students had an average mean increase from pretest to posttest on the ACAP. As such, the results suggest that the supplemental program was effective in improving third-grade students' ACAP reading scores. There was no statistically significant difference in performance on the posttest DIBELS composite based on race/ethnicity, gender, disability status, English language proficiency, or socioeconomic status. [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.]