Free speech recording samples of two groups of French SLI children aged 48 and 62 months (matched for MLU, 1.70) and two groups of French normally developing children aged 26 and 36 month (matched for MLU, 3.2) were compared to determine whether they showed a difference in the use of lexical categories. A category-by-category comparison showed few significant differences. For low MLU children, SLI produced significantly fewer infinitives, past participles, copulas, and demonstrative pronouns. For high MLU children, the difference persisted only in past participles use. As for English SLI children, French SLI children were delayed in their acquisition of verbs. However, the differences in the syntactic structure of English and French ruled out a syntactic explanation of the deficit. Phonetic problems seem to decrease with age, so they cannot be the only explanation behind the difficulties of SLI children, which probably involve cognitive problems such as processing limitations.