Book retelling has been frequently used as an indicator of children's reading proficiency. However, how children's performance varies across retelling narrative and expository texts and whether that has different implications for reading proficiency remains understudied. The present study examined 85 high-poverty second- and third-graders' retelling of narrative and expository books. A parallel coding scheme was developed to evaluate children's performance on retelling fluency, content, and language complexity. Children's retelling performance was compared across text types and analyzed in relation to reading proficiency. Findings revealed similarities and differences in retelling across text types, with narrative retelling containing a higher proportion of content-matched T-units, whereas expository retelling contained a higher proportion of inference generation and more complex syntactic structures. Moreover, indicators of reading proficiency were found to vary across text types. Findings highlight the distinct cognitive and linguistic demands posed by reading narrative and expository texts and provide implications for effective instruction and assessment.