Autismis a developmental disorder with variable severity, occurring at all levels ofcognitive ability and having a number of slightly different clinical presentations. It is associatedwith neuropsychological deficits that occur in other conditions also, but its patternmay be specific to autism. Genetic and environmental early insults to brain development areetiological determinants of the disorder. Brain circuitries important for social, communicative,and integrational purposes have been suggested to be dysfunctional in autism. There could be atleast two different pathways to autism, one connected with primary temporofrontal dysfunction(and late prenatal–early postnatal origins) and another linked to primary brain-stemdysfunction (and early prenatal origins). Further study of neurodevelopmental andneuropsychological processes in autism will help elucidate not only the pathological mechanismsinvolved in the specific syndromes but also the underpinnings of normal brain development.