Computers can provide active media for social group cognition where ideas grow through interaction within groups of people; function software to manage group discourse that produces a shared understanding, new meanings, and collaborative learning. Stahl's design studies concentrate on mechanisms to support group formation, multiple interpretive perspectives, and negotiation of group knowledge in applications as varied as collaborative curriculum development by teachers, writing summaries by students, and designing space voyages by NASA engineers. Stahl also discusses related issues such as the difference between the meaning of the decision at the group level and interpretation at the individual level, appropriate research methodology, philosophical directions for group cognition theory, and suggestions for further empirical work.