Purpose: The purpose of this study was to determine the effect of school district size on the academic performance of Texas students. Specifically addressed was the extent to which differences in school district size were related to differences in student academic performance. The academic performance of the three major ethnic groups (i.e., Black, Hispanic, and White) of students in Texas was ascertained. With respect to academic achievement, the subject areas of reading, math, science, social studies, and writing were analyzed. The relationship of school district size to student performance was examined for a 6-year time period, permitting the determination of trends, if present. Methodology: Utilized in the present study was a non-experimental, quantitative, causal-comparative quantitative research design. Archival data from Texas public school districts for the 2011-2012, 2010-2011, 2009-2010, 2008-2009, 2007-2008, and 2006- 2007 school years were obtained using the Texas Education Agency Academic Excellence Indicator System database. Black, Hispanic, and White student passing rates were analyzed for the Texas Assessment of Knowledge and Skills English Language Arts/Reading, Math, Science, Social Studies, and Writing examinations. School district size was defined as small-size (100-1,599 students), moderate-size (1,600-9,999 students), and large-size (10,000 students or more). Findings: Black, Hispanic, and White students enrolled in large-size school districts had statistically significantly higher passing rates on the TAKS English Language Arts/Reading, Mathematics, Science, Social Studies, and Writing examinations than did students enrolled in either moderate-size or small-size school districts for all six years. Moreover, in almost all cases, Black, Hispanic, and White students enrolled in moderate-size school districts had higher TAKS passing rates than their counterparts who were enrolled in small-size school districts. Overall, the effect size ranges for Black students were large whereas effect sizes for Hispanic were small and effect sizes for White students were moderate. Black, Hispanic, and White student academic performance was clearly related to the size of the school district in which they were enrolled. As such, the economies of scale theoretical framework was strongly supported by these results. Implications for policy and practice, as well as recommendations for further research, are provided. [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.]