An area of research with autism spectrum disorders (ASD), which has received a considerable amount of attention recently is early diagnosis. This phenomenon is due largely to encouraging results from intensive intervention programs for children at very young ages. While five types of ASD exist, efforts in this area have focused almost exclusively on autism. To date, the primary methods of identification have been evidence-based assessment scales using established criteria for differential diagnosis and cognitive/developmental descriptive studies, which attempt to tease out behavior patterns of infants who later evince ASD from their normally developing counterparts. A third focus, which is in early development, involves genetic studies aimed at establishing biological links. However, at present such procedures are not viable for diagnosis. Opinions are rendered on the earliest age at which children can be reliably diagnosed at present, and a review of practical considerations is provided. Future challenges and directions in ASD identification and diagnosis are discussed.