This qualitative and descriptive study partly explores a crucial aspect of child development, that is, story comprehension seen from the perspective of children’s elaboration of causal relations among story elements. The researcher met with 12 francophone preschool-aged girls (3;6 to 6;0 years old) from Québec City. At key points in the causal chain of story events, the researcher stopped reading to listen to what the children had to say about the construction of the relations they had elaborated until then. After reading, the same children answered four inference questions. Based on analyses which showed that children make causal relations more explicit during reading rather than after reading, it is reasonable to believe that dialogue during reading fosters the complexification of the expression of causal relations by preschoolers.