By age five children have acquired basic narrative skills and are able to report events temporally framed within a narrative structure. However, at least when they have to produce autonomous narratives on the basis of images, until 8-9 years many children have difficulties in telling coherent and causally-motivated stories, particularly when the internal states of the characters and a mentalistic understanding of the world are involved. The aim of this study is to contribute further results concerning the role of a dialogical intervention procedure soliciting children's attention on the reasons of the events of a story on children's production of complex mind-oriented narratives. To this effect, 140 French-speaking children aged 5 to 8 years (35 children at each age level) followed an experimental procedure devised in earlier studies. They were first exposed to five pictures (the "stone story" whose main point is a misunderstanding between two characters) presented sequentially. After the pictures had been removed, all children were requested to tell the experimenter the story (first narrative). Then, 25 children at each age level were asked questions soliciting the reasons of the key events in the story (the conversation group) while the other 10 (the control group) played a memory game with the story pictures and other similar cards. Then, all children were asked to narrate once again the story (second narrative). One week later children were asked to tell the story a third time (to test the stability of the eventual changes obtained immediately afterwards) and to tell a new story analogous to the stone story (to test the generalization power of the conversational intervention). Narrative skills were analyzed for causal and evaluative relations (explanations, internal states, false beliefs and overall coherence). Results show that from age six on, the conversation group improved, significantly more then the control group, the overall coherence and mind-oriented causal plot of the story in their second narrative. A relation between improvements and success in ToM tasks is observed. Results also show stability and generalization of the changes confirming the importance of the conversational intervention in improving the coherence of children's narratives and its usefulness as an assessment tool.