This paper proposes a new type of database for collaborative work. Known types of databases for collaborative work are databases of shared data and those of process data. A new type proposed in this paper is Group Activity Database (GADB). It contains history of group communication, which is used to analyze collaborative work. With a GADB, evaluation, user modeling, reengineering, simulation, and team awareness support will be helped. Evolution of groupware is supported by these activities. We adopt agent-based groupware architecture in order to realize open and distributed groupwork management. With this architecture, communication logs among agents or between agents and users are captured by a GADB for analysis.