Aggression and tantrums are common co-occurring problems with autism. Fortunately, positive developments in the treatment of these challenging and stigmatizing behaviors have been made recently with psychologically-based interventions. Evidence-based methods employ behavior modification, which is also often described as applied behavior analysis and has been at the forefront of these developments. Conceptually, researchers in the field note that many of the factors maintaining these challenging behaviors are communication related. A treatment that produces functionally equivalent reinforcement yet is socially appropriate has been proposed as a major thrust of intervention. In this article research-based treatments are reviewed for aggression and tantrums, the particular behaviors that have been effectively treated are discussed, and strengths and weaknesses of the intervention strategies are critiqued. A rationale for why these methods may prove to be an alternative to pharmacological interventions is presented. (Contains 1 table.)