The objective of this study was to probe neuropsychological mechanisms of social communication in children with Autism Spectrum Disorders (ASD) and children with Developmental Language Disorders (DLD). Due to overlap of symptoms that include social dysfunction, diagnostic boundaries between these two developmental disorders remain unclear. This study hypothesizes that these two groups of children differ in the characteristics and in the underlying mechanisms of their social issues. This study examines a wide range of neuropsychological domains in search of a relationship with social communication. A total of 75 children with ASD and 26 children with DLD are included. A cross-battery assessment of neuropsychological functions is conducted, and social communication is evaluated using the Social Responsiveness Scale (SRS). The neuropsychological profile for the ASD group differs from the DLD group, with the former demonstrating higher scores on Visual Processing and Comprehension, whereas the DLD group scores higher on Fluid Reasoning, Visual Processing and Processing Speed. Correlation analysis reveals that the association between neuropsychological domains and social communication differs between the groups. Children with ASD and DLD clearly have distinctive neuropsychological profiles-their strengths and weaknesses are not equivalent. Such results motivate broad assessment of neuropsychological functions, as this assists in differentiating ASD from DLD for theragnostic purposes.