Using two independent datasets provided by National Institute of Health funded consortia, the Collaborative Programs for Excellence in Autism and Studies to Advance Autism Research and Treatment (n = 641) and the National Institute of Mental Health (n = 167), diagnostic validity and factor structure of the new Autism Diagnostic Interview (ADI-R) algorithms for toddlers and young preschoolers were examined as a replication of results with the 2011 Michigan sample (Kim and Lord in J Autism Dev Disord 42(1): 82-93, 2012). Sensitivities and specificities and a three-factor solution were replicated. Results suggest that the new ADI-R algorithms can be appropriately applied to existing research databases with children from 12 to 47 months and down to nonverbal mental ages of 10 months for diagnostic grouping.