Changes to the DSM-5 Autism Spectrum Disorder (ASD) criteria raised concerns among parents and practitioners that the criteria may exclude some children with Pervasive Developmental Disorder (PDD). Few studies have examined DSM-5 sensitivity and specificity in children less than 5 years of age. This study evaluated 185 children aged 20-55 months with DSM-IV PDD or developmental delay. Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedule (ADOS) data was assigned to DSM-5 subdomains. Children displaying the required symptomatology were classified with DSM-5 ASD. DSM-IV clinical diagnoses were compared to DSM-5 classifications. Using combined ADI-R/ADOS information, sensitivity was 0.84 and specificity was 0.54. Comorbid behaviour and emotional problems were significantly lower in children with PDD that did not meet DSM-5 criteria.