Truancy, or unexcused absence, is a common problem facing nearly all high schools across the United States and other nations. Understanding how schools typically respond to student truancy and the relative effectiveness of these responses is an important, yet relatively unexplored area. Using a national extant dataset, this study examined which school disciplinary responses are most effective in reducing the reoccurrence and growth in truancy among ninth-grade students. Results revealed group differences in the odds of truancy reoccurrence. After controlling for student-level factors, out-of-school suspension (OSS) was found to significantly decrease the probability of future truancy. However, longitudinal growth models revealed that repeated and ongoing exposure to OSS actually accelerated the growth in truancy. Implications for schools and directions for future research are discussed. (Contains 6 tables and 1 figure.)