Several different methodological approaches that have been used in studying language in children with autism are outlined. In classic studies, children with autism are compared to comparison groups typically matched on age, IQ, or mental age in order to identify which aspects of language are uniquely impaired in autism. Several methodological problems are noted with this approach including (a) heterogeneity of the autism population, (b) mental retardation, (c) developmental change with age, and (d) sample size and ascertainment. An alternative strategy is suggested which focuses on identifying the complex expression of the language phenotype in autism across the full range of the syndrome. This approach explores within-group individual differences in language functioning, and recently identified distinct language phenotypic sub-groups within the autism population that are relevant to understanding the underlying genetic and neurobiological etiology of autism.