This qualitative study investigated how small group communication influences the development of shared mental models in a committee of public librarians addressing a problem-solving task. It examines the influence of communication themes, functions, roles, and rules on the group's development of shared mental models about the task and about team interaction. Data were collected over the course of a year from group meetings, email messages, group documents, and participant interviews and then analyzed using existing coding schemes and qualitative coding techniques. The findings indicate that within the group there was a strong superficial convergence around the task mental model and the team interaction mental model but a weaker convergence at a deeper level. Analysis of the group communication data shows that the group focused discussion on understanding the problem and identifying tasks, enacting group roles and rules that facilitated sharing information. The functions of their messages focused on task communication. The findings suggest that, in this group, communication themes most heavily influenced the development of a shared mental model about the task, while communication roles, rules, and functions were more influential toward the development of a shared mental model about team interaction. Implications for practice include adopting intentional tactics for surfacing mental models at various points in the group life and anchoring the emerging model within the collective cognition of the group through devices such as narratives, objects, or documentary materials.