Students who struggle to read at an early age are likely to continue struggling for not only the rest of their schooling, but the rest of their lives. Schools need to begin adopting research-based reading programs and measuring their effectiveness formatively throughout the school year. Research suggests that effective reading programs need to include phonics, phonemic awareness, fluency, vocabulary and comprehension. During the 2018-2019 school year, Wilson Fundations was implemented in K-2 at Summit Academy, a high-poverty Pre-K-8th grade school in Flat Rock, MI. The purpose was to uncover the potential effects of using Wilson Fundations as a reading program, while focusing on fidelity of implementation and the change in student achievement while the Wilson Fundations program was in place. To do so, I examined the teachers' fidelity of implementation, student performance on Wilson Fundations unit tests, and I also used statistical analyses to compare the growth of student achievement on NWEA MAP from Fall 2018 and Winter 2019 to Fall 2017 to Winter 2018. Previous research assessed the impact of Wilson Fundations on special populations, such as special education and students needing tiered reading intervention, but failed to measure the effectiveness of Wilson Fundations on student achievement across entire grade levels as a Tier 1 reading program. The results in this study suggest that student achievement in reading across all grade levels in K-2 experienced a significant positive change while the Wilson Fundations program was being implemented (p < 0.05). Based on the observations and RIT growth percentages on the NWEA MAP, the classrooms with the highest fidelity of implementation percentage also demonstrated the highest growth for their students. [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/en-US/products/dissertations/individuals.shtml.]