Psychotropic medication use and its relationship to autism spectrum core features were examined in a well-characterized but nonstratified North American sample (N = 1605) of children/adolescents diagnosed with autism spectrum disorders utilizing the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview–Revised, from the multisite Simons Simplex Collection. Analyses included (a) prevalence of psychotropic use (overall, and by classes), (b) correlations between prevalence of use and autism spectrum core features, age, and cognitive functioning, and (c) logistic regression to identify whether these factors were predictive of psychotropic use. Results indicated 41.7% ever used one or more classes of psychotropic medications, with attention deficit hyperactivity disorder medications used most. Small but significant correlations between psychotropic medication use and (a) social impairment (p < .001) and (b) repetitive behaviors (p < .001) were found. Overall, however, autism spectrum disorder core features are weakly related to medication use. Older children used more psychotropics (p < .001), and higher cognitive functioning was associated with less overall psychotropic use (p < .001). Logistic regression indicated that use of psychotropics was predicted by repetitive behaviors (both clinician-observed and parent-reported), age, and cognitive ability level. Limitations inherent to the Simons Simplex Collection sample, methodology, and the correlational analyses are discussed. Directions for future research include investigation of factors more influential than core symptoms on psychotropic treatment (e.g. parent perceptions, comorbid symptoms).