Over the past two decades, there has been an explosion of interest in autism and autism spectrum disorders. Knowledge and awareness of the condition has grown exponentially at all levels among the general public, parents, health professionals, the research community and, more recently, at parliamentary level. Alongside the increased understanding of these complex and disabling conditions is the acknowledgment of a broadening of the diagnostic criteria away from a narrow definition of autism to the autism spectrum with less clear diagnostic boundaries. Growing evidence of the importance of early diagnosis and intervention demands knowledge and skills from all professionals working with young children and in particular those involved in recognising early concerns about a child's development. This article outlines current clinical and research findings in relation to early diagnosis and considers the role of the paediatrician in this process. Reference is also made to the National Autism Plan for Children.