For collaboration in learning situations, it is important to know what the collaborators know. However, developing such knowledge is difficult, especially for newly formed groups participating in a computer-supported collaboration. The solution for this problem described in this paper is to provide to group members access to the knowledge structures and the information resources of their collaboration partners in the form of digital concept maps. In an empirical study, 20 triads having access to such maps and 20 triads collaborating without such maps are compared regarding their group performance in problem-solving tasks. Results showed that the triads being provided with such concept maps acquired more knowledge about the others' knowledge structures and information, focused while collaborating mainly on problem-relevant information, and therefore, solved the problems faster and more often correctly, compared to triads with no access to their collaborators' maps.