Autism spectrum disorder (ASD) frequently co-occurs with additional symptoms of psychopathology and challenging behaviors. While aggressive behaviors are often associated with attention deficits and hyperactivity in children with ASD, there is limited research on the impact that inattention/impulsivity and aggressive behaviors have on the developmental functioning of toddlers with ASD. However, identifying comorbidities is necessary for proper intervention. The aim of the current study was to examine the effects of inattention/impulsivity and aggressive behaviors on several domains of developmental functioning in infants and toddlers with ASD as measured by the "Battelle Developmental Inventory, Second Edition" (BDI-2). This study compared four groups consisting of 29 toddlers each: without inattention/impulsivity or aggressive behaviors (i.e., -I/-A), with inattention/impulsivity but without aggressive behaviors (i.e., + I/-A), without inattention/impulsivity but with aggressive behaviors (i.e., -I/ + A), and with both inattention/impulsivity and aggressive behaviors (i.e., + I/ + A). The results of the current study revealed significant group differences in Personal-Social, Communication, Motor, and Cognitive domains of the BDI-2. The significance and implications of the present study are discussed.