Purpose: Prior theoretical and empirical work has referenced several broad stages of narrative development, particularly in terms of young children's understanding of story structure. However, there is considerable variation in how story structure has been defined and assessed across these studies. The aims of the present study were threefold: (a) to test the unidimensionality of items designed to assess story-structure knowledge, (b) to examine story-structure item difficulty levels, and (c) to examine age-related progressions on individual story-structure components across 3-, 4-, 5-, and 6-year-olds. Method: Participants included 386 children (M = 4.8 years, SD = 11.67 months) from the Narrative Assessment Protocol study (http://www.narrativeassessment.com/), which was designed to revise a new narrative assessment tool for children between the ages of 3 and 6 years. Results: Factor analysis indicated that 16 of 21 items reflecting story-structure knowledge constituted a unidimensional construct. Individual story-structure item analyses further revealed that establishing subgoals and tracking the overall goals in the stories were particularly challenging for 3- and 4-year-olds. Conclusion: These findings hold implications for refinement of theoretical models of story-structure emergence in early childhood.