This chapter examines two cognitive issues in collaborative design: team cognition and communication. It commences with a detailed review of past research, before developing a new framework for design team cognition (DTC). This framework is built around an understanding of individual, team and distributed mental models and cognitive behaviours, including a consideration of different modes of communication and working. Furthermore, this chapter introduces a novel Cognitive-Social-Technical (C-S-T) system model, which elucidates the dynamic interplay among the three systems in digital design collaborations. In this chapter, the DTC framework is elaborated, and its implications for team cognition and communication are examined, through a discussion of the results of two experiments. The first uses the results of a protocol study of cognitive traits to reveal the importance of distributed mental models. The second uses protocol data from a study of cross-national teams to investigate design communication. This chapter contributes to the development of new methodologies for examining design teams and to advanced knowledge about design cognition and representation. These advances are potentially significant for supporting creativity and cross-cultural collaboration in teams.