Resurgence may be defined generally as the extinction-induced recurrence of previously learned response patterns. Understanding the conditions under which this phenomenon occurs has theoretical, clinical, and applied implications, particularly with respect to a related area of research on response-class hierarchies. In the current study, we examined resurgence with 2 participants who exhibited response-class hierarchies consisting of various topographies of severe problem behavior maintained by positive reinforcement. Baseline levels of responding were maintained by brief access to tangible items. In a second condition, reinforcement was produced by an alternative topography of severe problem behavior, and the initial topography was extinguished concurrently. When the reinforcement contingency for alternative behavior was removed, previously reinforced topographies recovered. This resurgence was specific to behavior that recently produced the reinforcer, which suggests that the recovery was not simply extinction-induced variation or emotional responding. The clinical implications of the results are discussed and related to results that have been produced in the laboratory by a variety of methods.