In this investigation, the degree to which student enrollment (i.e., school size) at elementary schools was related to student progress on the State of Texas reading and mathematics state-mandated assessments was examined for White, Black, and Hispanic students. Archival data available on the Texas Academic Performance Report were analyzed for the 2013-2014, 2014-2015, 2016-2017, and 2017-2018 school years. Inferential analyses revealed the presence of statistically significant differences, with below small to small effect sizes. Large-size schools had statistically significantly higher reading and mathematics progress rates than Small-size schools in 6 of the 9 analyses for White students. In 6 of the 9 analyses, school size was not related to student progress in reading or mathematics for Hispanic students. Small-size schools had statistically significantly higher progress rates in mathematics for Hispanic students than Moderate-size schools. Large-size, Moderate-size, and Small-size schools had similar progress rates in reading and mathematics for Black students in 8 of the 9 analyses. Implications for policy and practice, as well as recommendations for research, are provided.