Dynamic Assessment (DA) is recommended for testing bilinguals as it tests the child’s learning potential and not her or his previously acquired language knowledge. Thus, it allows language difficulties to be distinguished from difficulties related to a lack of L2 exposure. This study presents the findings of DA of morphosyntax in French-speaking monolingual and bilingual children, both Typically Developing (TD) and with Developmental Language Disorder (DLD). We examined whether DA was able to distinguish TD from DLD in children, irrespective of their linguistic group (mono- versus bilingual). Morphosyntactic skills were assessed in a sample of 37 children with DLD (19 bilinguals) and 42 with TD (18 bilinguals), aged from 5 to 12. We assessed six syntactic structures: simple sentences (SVO) in present and past tense, subject relatives, accusative clitic pronouns, passives, and object relatives. We provided graduated prompts if children were not able to produce the target sentences. The results confirmed the accuracy of our morphosyntactic task to disentangle children with TD from children with DLD, regardless of their linguistic group. Moreover, cutoffs for each structure as well as for the total score, as determined via ROC curves, indicated high sensitivity and specificity for children with DLD who had a documented morphosyntactic deficit.