Background: Teachers need to make sense of curricular materials and design instruction to ensure students will be positioned to pursue their own arc of inquiry in curriculum enactment. Whole-group discussions are crucial opportunities for curricular sensemaking, yet planning and enactment can be challenging. Methods: We used a single, revelatory case study approach with one focal teacher to research curricular sensemaking for epistemic agency in storyline materials. We identified episodes of pedagogical reasoning for epistemic agency in the teacher's pre- and postinterview responses and participation in discussion planning cycles (DPCs). This analysis revealed the recurrent sources of tension and ambiguity that the teacher grappled with concerning epistemic agency. Findings: The teacher made sense of two key sources of tension: curricular coherence and student coherence-seeking; equitable participation and incremental building of ideas; and one source of ambiguity: uniform or variable form(s) of epistemic agency in different discussion types. The teacher grappled with these tensions and ambiguity and learned to leverage them to position students with epistemic agency in their learning. Contribution: The teacher engaged in "curricular sensemaking for epistemic agency." This form of sensemaking involves the teacher's efforts to engage with students' emergent ideas and participation in their use of curricular materials.