Diagnosing autism and PDD-NOS at very early ages has become a major priority in the field of mental health. More recently, researchers have also come to realize the importance of identifying co-occurring conditions of psychopathology in this population. In the present study, 309 children between 17 and 37 months of age who had been identified as having either autism or PDD-NOS were screened for comorbid psychopathology. Using the psychopathology scale of the Baby and Infant Screen for Children with aUtIsm Traits (BISCUIT-Part 2), norms and cutoff scores for various forms of psychopathology (e.g., conduct problems, inattention, impulsivity, avoidance, anxiety, eating and sleep problems) were established. Additionally, frequency of items across factors was compared for autism, PDD-NOS and on atypically developing group of children without an autism spectrum disorder (ASD) (n = 460). All five disorders (tantrum, conduct behavior, inattentive/impulsive, avoidant behavior, anxiety/repetitive and eating problems/sleep) were more common in the autism group. Differences in the two groups were particularly striking for the anxiety/repetitive behavior and inattention/impulsivity factors. Implications of these findings are discussed. (Contains 5 tables.)