This study investigates grammatical development in French children with prelingual deafness after two to four years of cochlear implant (CI) use. We analyze to what extent lexical, prosodic and environmental factors play a role in the acquisition of grammar. Transcriptions of spontaneous language in thirty-four CI users (17 boys, 17 girls) were analyzed and compared to those of typically developing children (TD) matched on robust auditory experience in similar standardized situations. The interactions between language components (i.e., lexicon, prosody and grammar) were found to be similar to the interaction observed in typical children. The rate of grammatical development was significantly slow and strongly associated with environmental factors (e.g., socio-cultural level of the family). This suggests that late acquisition has no major consequences on the developmental patterns but that environmental factors play an important role in smoothing the path to adult language. Such results are compatible with a socio-cognitive view of language development, according to which language acquisition is a gradual process reflecting interactions between maturation and social experience.