Functional behavioral assessment (FBA) has been suggested for facilitating the development and effectiveness of behavior intervention plans. In this study, the researchers examined whether behavior intervention plans based on FBA information (function-based) were more effective than behavior intervention plans not based on FBA information (non-function-based) in affecting rates of problem behaviors displayed by two middle school students. Single-subject ABCBC designs were used to demonstrate a functional relationship between student responding and function-based and non-function-based behavior intervention plans. Results indicated that the use of FBA-based intervention plans was associated with greater improvements in lowering the number of problem behaviors. Implications and limitations for practitioners and researchers are discussed. (Contains 3 tables and 4 figures.)