To gain insight in the social processes that underlie knowledge sharing in teams, this article questions which team learning behaviors lead to the construction of a shared mental model. Additionally, it explores how the development of shared mental models mediates the relation between team learning behaviors and team effectiveness. Analyses were performed on student-teams engaged in a business simulation game. The measurement of shared mental models was based on cognitive mapping techniques. The results indicate that a team learning perspective provides insight in how people share knowledge. Particularly the team learning behaviors identified as co-construction and constructive conflict are related to the development of shared mental models. In addition, a shared mental model of the task environment in a team leads to improved performance. This underscores the importance of developing shared cognition in teamwork. (Contains 2 footnotes, 3 tables, and 1 figure.)