The transition from DSM-IV to DSM-5 criteria for autism spectrum disorder (ASD) sparked considerable concern about the potential implications of these changes. This study was designed to address limitations of prior studies by prospectively examining the concordance of DSM-IV and final DSM-5 criteria on a consecutive sample of 439 children referred for autism diagnostic evaluations. Concordance and discordance were assessed using a consistent diagnostic battery. DSM-5 criteria demonstrated excellent overall specificity and good sensitivity relative to DSM-IV criteria. Sensitivity and specificity were strongest for children meeting DSM-IV criteria for autistic disorder, but poor for those meeting criteria for Asperger’s disorder and pervasive developmental disorder. Higher IQ, older age, female sex, and less pronounced ASD symptoms were associated with greater discordance.