Since the passing of the No Child Left Behind (NCLB) in 2001, schools receiving federal funding must administer a state standardized assessment annually and meet performance standards in selected grade levels and content areas. Although it seems reasonable to assume frequency of teacher absenteeism affects student achievement, research has not consistently supported this assumption. Within the limited existing literature on the relationship between teacher absenteeism and student achievement, conflicting findings have been reported. The purpose of the study was to test the hypotheses that 8th graders whose mathematics and reading teachers had been absent for less than 10 days per school year (low absenteeism) would outperform those whose teachers had missed more than 10 days of being away from the classroom (high absenteeism) based on academic achievement in mathematics and reading, as measured by the 2017-2018 State of Texas Assessments of Academic Readiness (STAAR) test data. Results supported the hypothesis in mathematics, but not in reading. Mean difference effect sizes were computed to evaluate the practical significance of the findings. Due to non-experimental nature of the study, no causal inferences were drawn. The external validity of the study was limited to the participants. Theoretical and practical implication are discussed. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]