Background/Context: The importance of vision care begins at an early age, with doctors recommending screenings at multiple stages prior to reaching school age and throughout adolescence (Mathers et al., 2010; Solebo et al., 2015). Addressing unaddressed vision needs at an early age is particularly important due to the strong connection between student vision and student ability to access and engage in academic learning (Castanes, 2003; Glewwe et al., 2018; Pavithra et al., 2014). Yet the most disadvantaged students often lack eyeglasses, or the ability to access eyecare due to various barriers (Kemper et al., 2006; Slavin et al., 2018; Heslin et al., 2006; Qiu et al., 2014; Ruderman, 2016; Zhang, Cotch, et al., 2012; Zhang, Elliott, et al., 2012). Schools have been identified as sites for providing a host of non-school related services, including regular meals, dental screenings, asthma and chronic illness support, and vision care. For those students who cannot independently access vision care, school-based vision care for pre-school and early elementary students may provide a solution and a means of preventing later academic learning challenges. Objective/Research Question: It is established that the early grades are key to build a strong foundation for literacy. Interventions addressing student health conditions provide opportunities to examine effective methods of addressing the needs of students who otherwise would struggle to participate in academia. This study is designed to build on previous research linking school-based vision care to literacy learning through its focus on early grade students (prekindergarten - second). Setting: This study included a total of 102 schools serving preschool through second grade located in a mid-Atlantic urban district. Included elementary and elementary/middle schools enrolled predominantly black students (83.5%). Most students qualified as low-income (89.5%), but the sample included few English Language learners (EL) (4%) and a moderate number of students who qualified for special education (13.7%). Participants: The analytic sample included 1,383 students in preschool through second grade at baseline. Characteristics of these students were similar across the three cohorts (Table 1). Students were predominantly Black (76%), with 18% Latinx and 22% White. Fourteen percent of students were in special education and 12% were ELL. Students included in the analytic sample had to fail a vision screening, be prescribed glasses at the eye exam, have both baseline and post-intervention DIBELS composite test scores, and opt into the research study. Intervention: The school-based intervention included a vision screening conducted by the local health department for all students, an eye examination conducted by licensed optometrists in a mobile eye clinic at schools, and provision of eyeglasses for those diagnosed with refractive error. A consent form was sent to parents/legal guardians of students failing a screening, offering an eye examination. Eye examinations were subsequently conducted for students whose parents provided consent and diagnosed students could choose their preferred frames style and color. Students received their eyeglasses at school, and the intervention provided replacements as needed. Research Design: This cluster randomized study assigned elementary schools to one of three groups: intervention in the first, second, or third year starting in SY2016-17 (Cohort 1-3 respectively) (Figure 1). The treatment was a schoolwide intervention, and students' treatment status was determined by the school where they received school-based vision services. Data Collection and Analysis: Academic outcomes were English language arts (ELA) composite scores on the Amplify Dynamic Indicators of Basic Early Literacy Skills (DIBELS) test. DIBELS composite scores, based on initial sound, phoneme segmentation, nonsense word, and oral reading fluency subtests, vary from 13-287 points between kindergarten and second grade. Individual student test score data for SY 2015-16 through SY 2017-18 and student demographic data were obtained from the school district. Vision exam data were collected during the eye examinations. Vision data included the variables: prescription for eyeglasses, type of refractive error and severity of refractive error. To compare student achievement in English language arts for intervention and control students, we used hierarchical linear modeling following an intent to treat approach, where students were nested within the schools where they received their school-based vision services. The models analyzed program effects for each year separately, and controlled for student grade level, prior achievement, ethnicity, and blocking variables used in randomization (charter school status, school type, pilot study participation, school proportion of low-income and Black students, and whether the school served more than 25% Latinx students). Differential treatment effects for various student subgroups (gender, grade level, special education, and baseline achievement) were examined with interaction terms. Analysis was conducted using the R statistical software. Findings: The outcomes for all students are summarized in Table 2. For each cohort, there was a slightly negative non-significant impact, with effect sizes of -0.06 and -0.01 (p = 0.17, 0.89 respectively). Differential effects were explored for special education status, baseline achievement, grade level, and gender (Table 3). None of these four factors were found to moderate the treatment impact. Adjusted mean impacts and effect sizes for each of these categories of students are shown in Table 4. Discussion and Conclusions: The present study did not find a significant impact of the school-based vision care on DIBELS achievement scores. The study also did not identify differential effects by grade, gender, special education status, or baseline achievement. The lack of impacts may also be explained by poor consistency in the use of eyeglasses provided to students at such a young age. In addition, other research has pointed to inconsistent academic scores at pre-kindergarten and kindergarten levels being commonplace (Slavin et al., 2009). Future research should utilize additional tests that may be more sensitive to student growth, as well as further efforts to examine the degree to which the treatment received explains variations in outcomes. Limitations: This study was conducted in a real-world school-based program implementation context. The sample of students in the analysis were part of a larger study involving over 30,000 students over a wide age range. Consequently, variations in vision screenings and exams may have taken place in a manner that would not have occurred in a clinical trial setting.