A common form of collective memory is the group-authored document. Examining collaborative writing from the group memory perspective may yield important design and theoretical insights. This paper views collaborative writing as a cognitive process in which a portion of group memory is formalized. This view is the basis for expanding an existing model of individual writing to include collaborative writing and group memory. A collaborative writing tool is analyzed with the design implications from the expanded model. The analysis suggests that a group memory view of collaborative writing contributes useful insights that can guide the design of computer-based collaborative writing tools.