There is accumulating evidence that oxytocin, produced by the hypothalamus, plays a key role in social cognition and attachment, repetitive behaviors, and anxiety. Based on such data, abnormalities in the oxytocin system may be responsible for some of the core and associated deficits seen in autism. In this study, intranasal oxytocin will be assessed as a treatment for ASD in adults with high functioning autism or Asperger's syndrome. The effect of oxytocin vs. placebo will be assessed using measures of social cognition, repetitive behaviors, irritability, and anxiety. This study will also employ event related recordings to collect naturalistic data on some of the above symptom areas. An additional part of this study will examine the effects of oxytocin on gene expression.