Autism is characterised by deficits in social behaviour and communication, and is a cause of major lifelong disability. A novel intervention, oxytocin nasal spray, enhances social cognition and behaviour in humans, including in those with autism spectrum disorders. This project will determine whether oxytocin, taken twice daily over 8 weeks, improves social communication and interaction skills in toddlers with autism. This project represents a crucial step in developing an early intervention treatment for autism.