Abstract One critical issue arising in the educational use of collaborative learning concerns the teacher's difficulty in evaluating the contribution and participation of each student in group-work. This article aims to illustrate and discuss a methodology that enables evaluation of the collaborative learning process based on co-writing in a wiki environment. After considering the effectiveness of co-writing as a strategy of collaborative learning, the article will highlight issues regarding methods for evaluating each student's contribution to the collaborative process and to the group's overall action. A solution will be proposed to address the problem. It is based upon the elaboration of information traced automatically by wiki, employing survey grids and formulae developed ad hoc to calculate participation and contribution indexes. These tools will be illustrated together with their application in two university courses. Results demonstrate the added value given by the proposed approach to the evaluation process of co-writing. However, these findings also highlight critical issues and some possible remedies for the lack of specific wiki functions to automatically extract information required for quantitative analysis of the actions taken by members of the learning group.