Students with emotional or behavioral disorders (EBD) often display externalizing behaviors (e.g., aggression and defiance) and experience internalizing symptoms (e.g., anxiety and depression). When left untreated, these difficulties can result in negative outcomes for students in school and beyond. Cognitive-behavioral interventions (CBIs) offer a promising approach to address the needs of students with EBD. Extensive evidence demonstrates the effectiveness of cognitive-behavioral treatment in clinical settings, but fewer studies have explored the effects of manualized CBIs provided to students at school. The purpose of this study was to evaluate the effects of the Zones of Regulation, a widely-used CBI, on the externalizing and internalizing behaviors of middle school students served for EBD. This single-subject investigation implemented a multiple baseline design across five participants served in a self-contained special education classroom. Participating students received the Zones of Regulation lessons one-on-one from the researcher across six weeks of school. Data was collected through direct observations of the classroom, student reports on the Behavior and Feelings Survey, and teacher reports on the Strengths and Difficulties Questionnaire. Although students demonstrated declines in their use of verbal aggression, visual analysis indicated that there was no functional relation between the Zones of Regulation intervention and the reduction of externalizing or internalizing behaviors for participating students. The descriptive statistics for mean rates of verbal aggression across phases suggest that there were reductions in student externalizing behaviors, but these changes were not robust enough to meet the rigorous criteria of single-subject design. More research is needed to determine whether the Zones of Regulation program can reduce internalizing and externalizing behaviors when administered as a Tier 3 intervention for students with EBD. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]