This preliminary study investigated the use of the Function-Based Intervention Decision Model (Decision Model; Umbreit, Ferro, Liaupsin, & Lane, 2007) to improve teacher treatment integrity for a function-based classroom management plan. The participants were a special education teacher and three elementary-age students receiving special education services for emotional disturbance (ED) who engaged in disruptive, off-task behavior. This study was conducted in two parts: (a) a comprehensive functional assessment-based classroom management plan was systematically designed for a self-contained classroom of students with ED using the Decision Model, and (b) a functional assessment-based consultation (FABC) plan was systematically constructed using the Decision Model and implemented with the teacher participant to evaluate its effect on treatment integrity using a single-subject modified changing criterion design. Results of this study showed improvement in treatment integrity following the implementation of FABC, as well as improvement in student on-task behavior. Limitations and future directions are discussed.