The Understanding of Others’ Intentions (UOI) is a precursor of the theory of mind. The purpose of this study is to verify whether the absence of UOI is related to the Intelligence Quotient (IQ) or constitutes a typical characteristic of the autistic disorder, and if its presence could be a predictor of a positive symptomatologic evolution. To this aim, the UOI was evaluated in a sample of 100 non-verbal autistic children and in a sample of 50 non-autistic children with intellectual disability. The control group, in contrast to the children with Autistic Disorder, positively respondend to the test, thereby demonstrating the independence of the presence of the UOI from the IQ score. Assessing children with autistic disorder after 2 years of therapy, it was possible to verify that the presence of the UOI is a valid predictor of positive developments then highlighted by better ADOS scores.