Studies employing event-related brain potentials (ERPs) and functional magnetic resonance imaging (fMRI) were designed to study the effects of different types of language experience on the development and organization of neural systems important in language processing. Comparisons of cerebral organization in normally hearing, monolingual English speakers with that observed in hearing and deaf late learners of English suggest that while systems important in lexical/semantic processing are relatively invulnerable to delays in exposure to a language, the development of systems important in grammatical processing, including the specialization of the left hemisphere, is affected by early language experience. Studies of individuals who acquired American Sign Language (ASL) as a native language suggest that similar systems within the left hemisphere are employed in processing all natural languages independently of the structure and modality of the language acquired. These studies also reveal that additional areas within the right hemisphere can be recruited into the language system when the language depends on the perception of spatial location and motion. Studies of children acquiring their first language reveal that there is increasing differentiation of the neural systems important in processing the meaning of words and of the areas important in lexical and grammatical processing and that these increases in specialization are linked to language abilities rather than to chronological age per se. Further studies suggest that developmental language impairment can result from alterations in one of several different systems important in language, and that some indices of these functional neural systems may be predictive of language impairment.