Functional behavior assessment (FBA), although mandated by federal law in situations involving students with emotional and behavioral disorders, is not well defined in the literature in terms of how it should best be undertaken in widespread practice in schools. Functional behavior assessment can be defined as a process for determining the reason or reasons why a student engages in inappropriate behaviors by identifying predictable relations between the behavior and the environmental conditions in which it occurs. Unfortunately, highly technical terminology and a poorly defined process have turned a valuable technology into more unnecessary bureaucratic paperwork in its widespread implementation. This article describes how FBA can be applied in a straightforward manner for students with challenging behaviors. The process is broken into steps and described using a case study from a real classroom context. Detailed examples help guide practitioners through some of the more likely roadblocks to creating and implementing FBAs. (Contains 2 tables and 2 figures.)