There is limited research available on the relationship between student attendance and academic achievement in secondary school. This quantitative, non-experimental study, conducted within a South Dakota high school of students in grades 9-12 during the years 2006-2012, examined the relationship between student attendance and academic achievement measured by mathematics achievement scores, reading achievement scores, and GPA. It explored the significance of the relationship between attendance and achievement for males and females, students receiving special education services and those who do not, and students who are economically disadvantaged and students who are not. Attendance records for the years 2009-2012 were collected from the attendance software, PowerSchool. Records prior to 2009 were extracted from students' cumulative folders. Data regarding reading and mathematics achievement scores were extracted from tests administered during the 11th-grade year. The GPA, calculated following the completion of four years of attendance, was collected from the students' transcripts at the end of the 12th-grade year (N=610). Investigation into the relationship between attendance and achievement revealed the correlation between student attendance and reading achievement was less than that of mathematics achievement or GPA. The correlation between student attendance and reading achievement revealed a significant but weak effect, while the correlation between student attendance and mathematics achievement was significant but moderate and between student attendance and GPA revealed a significant but strong. This study found that there was no difference in the relationship between student attendance and academic achievement between males and females. The study revealed student absences had more of an effect on students that do not receive special education services than those that do receive special education services in reading and mathematics achievement. The study revealed there was a difference in the relationship between attendance and achievement between students that are economically disadvantaged and students that are not economically disadvantaged in mathematics achievement. [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.]