The application of school-wide positive behavior support (PBS) in an alternative school setting was investigated. The main purpose of this 1-year evaluation case study was to evaluate the impact of a high school PBS model on school-wide discipline outcomes (incident reports, teacher reports); and to gain an increased understanding of the psychological well-being and adjustment of students in the alternative education setting, specifically as it relates to individual student's participation in/ or response to this particular intervention (PBS). The impact of intervention implementation was measured using quantitative and qualitative methods. The overall level of implementation of PBS during the first year of implementation reached 69% as measured by the School-wide Evaluation Tool. The results indicated that the overall number of incident reports did not significantly differ between the baseline year and the implementation year. However, there were some reductions in defiance-related behaviors. Students were divided into two groups: "responders" and "non-responders" and student's response to a number of measures (obtained prior to intervention) assessing their perception of individual, school, social/community, and home systems were compared. Results indicated that the individual system model and the school system model were able to distinguish between responders and non-responders. Specifically, within the individual system model, hostility, destructive expression of anger, and depression made unique significant contributions to the model. Within the school system model, academic self concept, attitude to teachers and attitude to school provided significant contributions to the model. A logistic regression revealed that hostility, destructive expression of anger, depression, academic self concept, attitude to school, and attitude to teachers, as a group, were able to distinguish groups from one another. These findings seem to indicate that PBS had some impact on improving outcomes for specific behavior types (defiance) for students in alternative school settings. However, since these students tend to experience numerous mental health concerns, particularly those classified as "non-responders," more intensive supports in conjunction with universal interventions are necessary.