Current theories concerning psychological deficits in children with autism were reviewed. The author argues that, to the extent that there is a single area of primary impairment, it must lie in the domain of social attachment, including the impetus to communicate. Some recent data support this position. The findings from research with animals and humans suggest that the amygdala might be crucially implicated in the social deficits in autism. Human communication represents the merging of two evolutionary lines of development, that of mammalian communication systems and that of the primate capacity for internal representation. Such a view has direct implications for the nature of the communication deficit in autism.