Collaborative storyboarding, with a focus on aggregating designers’ expertise in the storyboarding process, offers the opportunity for a group of designers to make progress toward creating a visual narrative for a new interface or technology, but it requires the designers to work together to explore ideas, differentiate between options, and construct a common solution. Important in collaborative storyboarding is the shared understanding that emerges among the designers and the obstacles they face in establishing that understanding. This paper defines a model for collaborative storyboarding, presents a study that explores group interactions in collaborative storyboarding, and analyzes the interactions using the distributed cognition and common ground theories. Our findings demonstrate that joint interaction and enthusiastic efforts within each phase lead to active information exchanges and shared understanding among the members of the group.