The increased prevalence of autism spectrum disorder (ASD) and its detection during the first 3 years of life have substantial relevance for early intervention. The purpose of this article is to summarize current scientific and policy information on early identification and early intervention for infants and toddlers with ASD and their families. Following a brief overview that provides basic information about ASD, the authors discuss early warning signs of the disorder and available screening and diagnostic tools. Finally, they highlight focused intervention practices and comprehensive treatment models appropriate for infants and toddlers with ASD, as well as issues affecting the delivery of effective early intervention services to children and families. (Contains 2 tables.)