In this study we describe the levels of clinically significant behavior in participants with Sotos syndrome relative to three matched contrast groups in which the behavioral phenotype is well documented (Autism Spectrum Disorder, ASD; Prader-Willi, and Down syndromes). Parents and carers of 38 individuals with Sotos syndrome (mean age = 17.3; SD = 9.36), completed questionnaires regarding self-injury, aggression, repetitive behavior, autism spectrum phenomenology, overactivity, impulsivity and mood, interest and pleasure. Individuals with Sotos syndrome showed an increased risk of self-injurious behavior, physical aggression, and destruction of property relative to the Down syndrome group but not a greater risk of stereotyped behavior. Impulsivity and levels of activity were also significantly higher relative to those with Down syndrome and comparable to those with ASD. A large proportion of participants met the cut off score for ASD (70.3%) and Autism (32.4%) on the Social Communication Questionnaire. Social impairments were particularly prominent with repetitive behavior and communication impairments less characteristic of the syndrome. Interestingly, preference for routine and repetitive language were heightened in individuals with Sotos syndrome and the repetitive behavior profile was strikingly similar to that observed in individuals with Prader-Willi syndrome. These findings build upon previous research and provide further evidence of the behavioral phenotype associated with Sotos syndrome.