The current study added to the growing literature on school-based dialectical behavior therapy (SB-DBT) by examining the implementation of a SB-DBT intervention with high school students. It was hypothesized that students' perceived emotion regulation and adaptive coping would improve whereas reports of dysfunctional coping would decrease from pretreatment to posttreatment. Furthermore, it was predicted that grade point average (GPA) and attendance would increase throughout the intervention. Treatment groups receiving comprehensive and modified SB-DBT allowed for the exploration of the intervention's usefulness in a Multi-Tiered System of Support (MTSS) among at-risk and high-risk populations. Archival data from 2018-2019, which was collected as per the school's intervention evaluation process, was utilized to assess the research questions and hypotheses. The participants included 15 individuals between Grade 9 through Grade 11 who participated in SB-DBT that year. There were three active groups that varied in modalities offered, length of treatment, or modules presented. Trend analyses were used to analyze individual and group outcomes on the Difficulties in Emotion Regulation Scale (DERS-16) and Dialectical Behavior Therapy Ways of Coping Checklist (DBT-WCCL), as well as across GPA and attendance. Group results were presented. Findings indicated that emotion regulation improved for comprehensive groups, but declined in the modified treatment. Two conditions showed increased DBT skill use and reductions in maladaptive coping. Grades and attendance did not reflect stable progression throughout the intervention. Observations suggest that SB-DBT has the potential to meet students' varied needs, although careful consideration must be taken when modifying treatment to maximize outcomes. [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.]