Contrary to scholastic failure, the question of language insecurity in adult native speakers has not attracted much attention. Beyond the obvious political and ideological debates, the question for research is to understand whether increased linguistic mastery can allow speakers to communicate in an efficient manner with any given interlocutors. Analysis of collaborative discourse in low educated native speakers shows that, as well as lexical and syntactic issues, problems linked to interaction can appear that impede the flow of exchanges. These give rise to collaborative discourse construction practices that require numerous readjustments and conversational negotiations.