Our activities are becoming more and more computer-mediated. For documenting these activities, it is no longer sufficient to automatically record their traces. In this paper we introduce the redocumentation process of computer-mediated activity as a narrative construction that ties together the content of activity traces and the users’ knowledge in describing their activities in new easily exchangeable documents. We present a generic semi-automatic approach for this process, which is based on rhetorical structure theory. This approach uses formal models for process input and output, and handles the process through two main phases: an automatic phase to generate a fragmented document from traces as a first description of the activity and an interactive phase to allow the user to tailor this first description according to his particular needs and choices. We also present ActRedoc, a tool developed for text-based redocumentation, for which a first evaluation was conducted.