While prior research has demonstrated the importance of narratives as tools for young children's science learning, limited research has considered how narratives can be integrated into the design of science learning environments to support opportunities for children to engage in science practices. We designed four [approximately] 30-minute preschool science programs for museum settings built around narratives from children's science storybooks. Video-data was gathered for three to four iterations of each program with preschool-age children (3-to-5 years) at a small children's science museum and local preschools. Using conjecture mapping as our analytic framework, we found that story-driven programs provided children with opportunities to co-construct evidence-based explanations as mediated by verbal and gestured discourse, engagement in investigation of science phenomena, and generation of representations. Importantly, results suggest that while elements of the storybooks' narrative (structure, events, and agency) supported children's co-construction of explanations, the stronger influence on children's explanations was through the way the storybook's phenomenon was integrated into the program. These findings can help educators better understand the role narratives may play in young children's science learning.