We investigated longitudinally the co-constructed narratives of 31 mother-child dyads collected when the children were 3-, 4-, and 5-years old, examining the dual development of child conversational and narrative discourse skills and the impact of maternal verbal assistance. Linear mixed-model analysis revealed that children's developmental trajectories toward successful responsiveness and contingency differed as a function of maternal scaffold type. Qualitative analyses revealed that children's use of both narrative and conversational skills during narrative co-construction made it difficult for the dyad to participate in effective co-construction. We discuss the challenges children face when simultaneously employing their understanding of appropriate participation in conversation and their knowledge about what makes a narrative structurally coherent, as well as the strategies that mothers can use to assist their children in navigating the conversational demands of narrative co-construction. (Contains 4 figures, 3 tables, and 4 footnotes.)