The concept of materiality has acquired great significance in sustainability reporting. Through the theoretical bricolage of boundary objects and boundary work and drawing upon 91 interviews, we trace materiality’s evolving role across four interconnected episodes. Our findings show that materiality begins as a multivisionary object that draws the attention of largely unconnected groups. As different actors become more aware of each other, materiality becomes a meeting point object, and then a discursive and bridge-like object for them to talk about their relationships. However, the subsequent escalation of competitive boundary work turns materiality into a divisive institutional object that inhibits cooperation. Moving beyond a view of materiality as a way to distinguish significant information within corporate reports, our analysis fleshes out the visionary and relational roles that materiality has performed in sustainability reporting for a broad range of field-level actors to see themselves and their relationships to others in new lights.