Mandatory grade retention for poor-performing readers has been a disputed practice for decades. Since the early-2000s, state-level mandatory grade retention policies have proliferated. In 18 states and Washington, D.C. mandatory grade retention exists for students in the third-grade who fail an end-of-year standardized reading exam. These policies are based on research that suggests students who do not read by the third-grade are at much greater risk of dropping out of school prior to receiving a high-school degree. Mandatory grade retention policies use a gatekeeper mechanism at the end of the third-grade to ensure that students who are not reading at a set threshold are required to repeat the third-grade the following year. There has been an abundance of research on the effectiveness of student grade retention at the individual level, with mixed conclusions. However, there is little research on the effectiveness of state-level mandatory grade retention policies on school-level improvement in reading scores over time. Whether state-level mandatory grade retention polices are effective at promoting stronger reading at the school-level was the subject of this research. In this study, I evaluated a mandatory grade retention policy in North Carolina using latent growth curve modeling. Using an SEM framework, I identified whether a school's use of student grade retention in the third-grade improved that school's fourth-grade average reading scores over the period of the state-level mandatory retention policy roll-out. I leveraged data from the National Center for Education Statistics' Common Core of Data, the Civil Rights Data Collection, and school-level standardized test scores to evaluate whether the effect of grade retention on test scores differed based on the school-level characteristics of student racial composition, the locale of the school, and whether the school increased retention over the period analyzed. I estimated the effects of retention over three timepoints: prior to mandatory retention being passed by the state government, following passage but prior to implementation, and following policy implementation. Through investigating these three timepoints and comparing to one another, I drew conclusions about effects of different phases of the policy roll-out. I created two latent growth curve models. The first model measured whether retention rates increased from 2009 to 2013, prior to policy implementation, and between 2015 and 2017, after policy implementation. The second model tested whether school-level standardized reading scores changed over time. Using these two models, I found that while third-grade state-level student retention rates decrease overall from 2009 to 2017, when controlling for school-level characteristics, school-level retention rates increased over this period. This was associated with higher variability in school-level retention rates after implementation of North Carolina's third-grade reading law. There was no evidence to suggest that subsequent school-level reading scores improved due to mandatory retention or due to changes to school-level retention rates, regardless of the school student population or school locale. Recommendations for state-level mandatory retention policy are proposed, including maintaining reading supports for K-3-grade students while incorporating a more uniform promotion model, where students who struggle in reading are given intensive intervention while still learning new content and remaining with their age-level cohort the following year. [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.]