Students enrolled in special education programs exhibit chronic disruptive and aggressive behavior, and teachers spend the majority of their time on discipline. Behavior intervention programs help teachers manage emotionally disabled (ED) students, teach them acceptable social skills, and improve academic performance. However, teachers are not often asked for their input on training and implementation, and few studies have been conducted on teachers' evaluations of these programs. This mixed-method study investigated teachers' evaluations and perceptions of a positive behavior intervention support program (PBIS) at a Northeastern school for middle school ED male students. Participants were comprised of a convenience sample of 10 experienced special education middle school teachers. Three research questions were formulated, one quantitative, with corresponding hypothesis, and two qualitative. Quantitative data were collected with two instruments, and qualitative data were collected with an interview protocol and in-depth interviews. Descriptive statistical methods (frequencies, percentages, means) were used for quantitative data analysis, and qualitative methods (coding of interview data, synthesizing of themes and patterns) were used for qualitative data analysis. Quantitative results showed that the null hypothesis was rejected: the majority of teachers described their concerns and value of the program in terms of agreement or strong agreement. Qualitative results indicated that teachers expressed strong enthusiasm for the positive effects of the program on their teaching and students' improved academic and interpersonal skills. Teachers observed students' reduced aggressive behavior, fewer disciplinary referrals, greater focus on learning, and interactions with peers. Teachers also recognized the need for consistent training and greater parental support. It was concluded that the findings supported the value of the program, the need for continuous professional training, and the benefit to both teachers and students from this type of program. Recommendations for future research were made for replication with larger and more diverse samples, other schools, and different grade levels. Additional recommendations included revision of the instrument, systematic evaluations of the program, and inclusion of parent and student feedback.