Oxytocin is a brain peptide that appears critically important in normal prosocial behaviors. Oxytocin system changes in mice lead to some autistic-like behaviors. Several different types of genetic evidence suggest that the oxytocin receptor gene is involved in autism. Multiple studies show that oxytocin can enhance social judgment and prosocial behaviors in people with autism or typical development. Two small studies in people with schizophrenia suggest brief oxytocin treatment is safe. The first goal of this study is to obtain preliminary data necessary to inform the design of a large conclusive study of the benefits of oxytocin in autism. Other goals are to see if 1) recently discovered non-inherited differences in DNA around the oxytocin receptor in autism have functional effects on oxytocin receptors and 2)if measurements of oxytocin system molecules appear related to severity of social problems or benefits in autism. The investigators will treat 24 youth 3-17 year old who have autism and any level of cognitive functioning with oxytocin or saline nasal spray 2x/D for 2 months. Neither the practitioner nor the participants will know who gets oxytocin and who gets saline. Afterwards, everyone will receive oxytocin for 2 months. The researchers will determine how many participants would need to be in a larger study to get a clear answer about whether oxytocin is beneficial and how best to measure improvements due to oxytocin. DNA changes will be examined to see if they control the number of oxytocin receptors and if they relate to symptoms or oxytocin response. It is expected that oxytocin will be beneficial and that DNA changes will correlate with the amount of oxytocin receptor made. Measurement of oxytocin system molecules will identify a distinct group of people with social disabilities in autism and will predict who will respond to oxytocin treatment. This is one of the first potential treatments for autism that is based on information about biologic processes that may cause core autistic symptoms. The results will inform the design of a conclusive study that gives a clear answer about whether oxytocin has benefit in autism. This pilot study may also help develop a blood test that would tell us who is most likely to respond to oxytocin treatment. Finally, the data will increase understanding about how non-inherited changes in the DNA around the oxytocin receptor affect people with autism.