The problem addressed by this study was to determine the influence of high school start times on students' academic achievement and precisely how this impacts the scores students received on the Biology I End of Course Exams. It also determined if there was a difference in influence between males and females. This was determined by comparing the average school test score in the state versus the different school start times and the average scores of males and females versus school start times. Three one-way ANOVA tests were used to determine school start time's influence on test scores. The data shows that school start time significantly affects Biology I End of Course Exam scores and moderately affects males and females. Schools that started from 8:31- later averaged 13.5 points higher than those that started from 7:30-8:00 and 8.4 points higher than those that started from 8:01 to 8:30. The results for males and females were similar. Males that started school from 8:31- until averaged 14.9 points higher than the schools that started from 7:30-8:00 and 9.9 points higher than schools that started 8:01 to 8:30. Females that started school from 8:31- until averaged 13.3 points higher than schools that started from 7:30-8:00 and 8.1 points higher than schools that started 8:01-8:30. I was able to determine that, with all things being equal, school start time influenced Biology I End of Couse Exams and the test scores of both males and females. This problem may be solved by starting school or the Biology I End of Course Test later during the school day. [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.]