Although it seems reasonable to assume frequency of teacher absence affects student achievement, research has not consistently supported this assumption. This quantitative, non-experimental study investigated the relationship between teacher absenteeism and student achievement in mathematics and reading in one high-performing suburban elementary school district serving three affluent Midwestern communities. Focusing on students in grades 3-8, this study also determined whether significant differences in mathematics and/or reading achievement scores existed among students whose teachers were absent for varying numbers of days during the 2010-2011 school year. Frequency of absence from the classroom for any reason of mathematics and reading teachers (n = 114) and students' scaled scores (n = 2,741) on the mathematics and reading subtests of the Illinois Standards Achievement Test were obtained from district records. Students' achievement scores were sorted according to the number of absences incurred by their math and reading teachers. A significant but weak correlation was found between teacher absenteeism and mathematics achievement. Analyses of variance revealed differences in mathematics achievement based on frequency of teacher absence were significant for all students in grades 3-8, for intermediate students (grades 3-5), and for special education students. Surprisingly, mean scores of students whose teachers were absent the least were significantly lower than scores of students whose teachers were absent more frequently. No correlation was found between teacher absenteeism and reading achievement. Analyses of variance revealed significant differences in reading achievement based on frequency of teacher absence were significant for all students in grades 3-8, for intermediate students (grades 3-5), for middle school students (grades 6-8), and for special education students. Similar to the unexpected findings in the area of reading, mean mathematics scores of students whose teachers were absent the least were significantly lower than scores of students whose teachers were absent more frequently. [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.]