Considerable clinical evidence suggests that autistic children lack the normal ability or desire to engage others socially, as indicated by their poor social skills and inappropriate use of language for communicative purposes. Specifically, these children seem to lack normal amounts of social-emotional interest in other people, leading perhaps to a decreased initiative to communicate. This paper summarizes experimental evidence supporting a neurological theory, which posits that autism, at least partially, represents in the brain, such as brain opioids. These substances modulate social-emotional processes, and the possibility that blockade of opioid activity in the brain may be therapeutic for early childhood autism is discussed.