Autism or autism spectrum disorder (ASD) is characterized by social and communication deficits and repetitive behaviors/restricted interests. Typically, autistic disorder, Asperger syndrome, and PDD-NOS are included under the umbrella of ASD. When all forms of the syndrome are taken into consideration, ASD affects up to 1 in 150 individuals. There are currently no drugs approved for the treatment of social difficulties in autism. Oxytocin is a hormone produced in the brain. It is responsible for labor and breastfeeding and, for the longest time, it was considered to be a female hormone. However, scientists have recently reported that oxytocin in the brain is important in helping us understand others and their emotions, as well as relate to others. It may have an effect on our anxiety levels and on some repetitive behaviors. On an earlier small study, we showed that taking oxytocin as a spray through the nose twice a day helped adults with ASD understand people's emotions and reduced their repetitive behaviors, while being well tolerated. Based on the above, we believe it is appropriate that we start testing this medication in young individuals with autism. We propose to start with older children and adolescents, ages 12-17, who meet standard diagnostic criteria for autistic disorder or Asperger syndrome and have cognitive abilities within the typical range. The study will first recruit approximately 15 children and adolescents to make sure that the dose used in the adult study is still safe for these kids. Then 60 children and adolescents will receive either the oxytocin spray or a placebo spray for 12 weeks, while the investigators at University of Toronto/Bloorview Kids Rehab and University of Illinois at Chicago will monitor the effects of the spray, both good and bad. At the end, children who were given placebo can choose to try the oxytocin spray if they so wish. If we find oxytocin to be effective in our group, we will have more data to suggest that it or a similar compound may be of use to treat social difficulties in children and adolescents with autism. Because we will only recruit high functioning children ages 12-17, we can only generalize to children with similar age and cognitive levels. We do not anticipate any major side effects, given that breastfeeding women have been using this formulation for a long time. However, because we have not treated children and adolescents with this medication, we will be very vigilant in recording anything that could potentially be harmful, whether we think it is related or not to medication. By comparing the oxytocin group to the placebo group, we hope to be able to report on the safety of intranasal oxytocin in this group. We expect to be able to report clinically meaningful results by September of 2013.