This study investigated the relationship between school start times and academic and school behavioral outcomes among adolescents. Academic achievement test data from five high schools in a Southwestern school district were compared prior- and post- a school start time change. Behavioral discipline reports were also examined to determine if earlier start times resulted in more behavioral problems for students. Results indicated minimal changes in academic achievement scores, with some significant differences between school start times when examining students' performance by pass/fail categories. Behaviorally, there were statistically significant differences between school start times with regards to high frequency referrals (i.e., attendance-related and defiance and disrespect towards authority), and total Office Discipline Referrals. Results are discussed in relationship to previous research on sleep and school start times along with the implications for adolescent school performance.