Narrative competence can be considered an indicator of children's knowledge about other people's minds. The present study investigates the relations between, on the one hand, children's narrative competence and their second order language of mind (comprehension of deception) and, on the other, their developmental trends from kindergarten to primary school. Participants in the study included 142 Italian-speaking children (63 attending their last year in kindergarten and 79 attending first grade in primary school). Children were given a narrative task containing a deception. The ability to detect and comprehend deception increased significantly from kindergarten to primary school. Regression analyses showed that narrative competence influences the comprehension of deception. Findings confirm the importance of narratives as a research tool and the possibility to use mental language to assess different levels of theory of mind mastery.