Functional behavioral assessment (FBA) is an assessment procedure used to identify the reasons for children's misbehavior. In this article we provide an overview of one approach to FBA known as multimodal functional behavioral assessment (MFBA) that provides a comprehensive examination of the causes of children's disruptive behavior. The literature for the causes (functions) of behavior identified in MFBA is reviewed as applied to children with the educational classifications of emotional disturbance and social maladjustment. Differences between educational classifications for each function are highlighted with the purpose of informing treatment selection in school settings. © 2004 Wiley Periodicals, Inc. Psychol Schs 41: 867–877, 2004.