Early diagnosis of Autism Spectrum Disorders (ASDs) is crucial so that early intervention services, which have been found to best alleviate symptoms of ASD in children, can be implemented. Currently, the "Modified Checklist for Autism in Toddlers" ("M-CHAT") and the "Baby and Infant Screen for Children with aUtIsm Traits-Part 1" ("BISCUIT-Part 1") are the most widely researched ASD measures in early childhood. However, the "M-CHAT" provides many false positive results as it is solely used as a screening instrument as opposed to a diagnostic measure, while the "BISCUIT-Part 1" appears to have more diagnostic fidelity. The current study examined 243 toddlers who failed the "M-CHAT" screener and were therefore referred for further evaluation. Upon further evaluation, 141 of the toddlers were diagnosed with an ASD while the remaining 102 were not. Characteristics differentiating these two groups on the "M-CHAT," "BISCUIT-Part 1," and "Battelle Developmental Inventory, Second Edition" ("BDI-II") were examined with analyses supporting the hypotheses that children in the ASD group had higher "M-CHAT" and "BISCUIT-Part 1" scores in conjunction with lower "BDI-II" scores. Based on these results, the incremental predictive validity of the "M-CHAT" was assessed; the "BISCUIT-Part 1" was found to be more accurate in arriving at ASD diagnoses. The implications of these findings are discussed. (Contains 3 tables.)