There has been a marked increase in interest in early identification of young children with and at risk for autism. This interest has reflected advances in research as well as an awareness of the potential for major changes in long-term outcome as a result of intervention. Several issues have complicated these efforts. There continue to be challenges to implementation of effective screening and diagnostic approaches in young children. Although the body of evidence-based research on treatment has increased, it remains limited. Despite these issues, important findings have emerged that may assist in fostering better approaches to screening, diagnosis, and documenting treatment impact.