Motor disturbances are often observed in individuals with autistic spectrum disorders (ASDs) and recognized as diagnostic features of these disorders. The movement disorders characteristically associated with autism include stereotypies and self-injurious behavior. Yet, individuals with ASD may also be at the risk for catatonia. Although not as frequent as stereotypies, up to 17% of older adolescents and adults with autistic disorder may have severe catatonic-like symptoms. Catatonia may be a comorbid risk factor of autism that warrants further empirical and clinical evaluations. Clinicians may need to be attentive to more subtle signs of catatonic-like symptoms in individuals diagnosed with ASDs, especially as they enter adolescence and young adulthood. Stress has been implicated as a possible precursor for symptoms; however, its role has not been empirically proven as a potential risk factor. Clinicians might also need to assess for signs of significant declines in motor movements, as this appears to be a useful diagnostic indicator of catatonic-like symptoms. The literature on stereotypies and autism is more extensive than for catatonia and ASDs, probably because of the higher rate of stereotypies with autism. Explanations for the occurrence of stereotypies range from genetic to behavioral contingencies, with evidence for a multifactor explanation. Assessment measures often include items that assess for stereotypies to aid with diagnosing these symptoms in individuals with autism. Treatment for stereotypies is largely behavioral at the present time and requires consistent reinforcement of treatment gains to manage the symptoms successfully. An important area of future research in autism is the relation among different types of motor abnormalities, including stereotypies and catatonia. © 2006 Elsevier Inc. All rights reserved.