It is well recognized that children with "autistic features" constitute a very heterogeneous population. There is a growing consensus that the core symptoms seen in autism include deficits in: (1) social/affective/behavioral functions, (2) developmental language disorders with concomitant deficits in interpersonal communication, and (3) play/preferred activities/preoccupations which have a repetitive or stereotypic quality. The definition of the boundaries of "autism" as opposed to other related pervasive developmental disorders is widely debated among clinicians and research investigators alike. In the present paper, it is argued that autism is a cover term for a spectrum disorder with similarities and differences in the clinical presentation of preschool children. A model for subtyping the autistic spectrum disorders is suggested.