Functional communication training involves teaching students who display severe challenging behavior to appropriately request the stimuli previously obtained by their behavior problems. In the present study, we evaluated the effectiveness of functional communication training as an intervention for the aggression, self-injury, and tantrums exhibited by three students. Assistive devices were used to augment their communicative skills. Following an assessment of the function of their challenging behavior, the students were taught to use their devices to request the objects and activities maintaining their behavior (e.g., social attention, breaks from work). Multiple baseline data collected across the three students indicated that not only did the students use their devices successfully, but the intervention also reduced their challenging behavior. In addition, data on how the students were affected showed that they displayed increased positive facial expression following the communication intervention compared with before training. These results are discussed in the context of recent efforts to develop effective interventions for severely challenging behavior for persons with limited communication skills.