Autism spectrum disorders (ASD) in children are a serious and complex set of conditions that researchers have been attempting to quantify for many decades. In addition to the core symptoms of ASD, comorbid psychopathology is often present as well. Despite this fact and despite the many attempts to develop scaling methods for ASD, little has been done to develop tests specific to childhood psychopathology in ASD children. In this study we describe the initial psychometric properties of a new scale designed specifically to fill this assessment need, the Autism Spectrum Disorders-Comorbid for Children (ASD-CC). One-hundred and thirteen children with ASD between the ages of 2 and 16 years were assessed in order to determine interrater, test–retest, and internal reliabilities of this new scale. Implications of these promising findings with respect to further development of the ASD-DC are discussed.