The educational applications of wikis are becoming very popular among instructors and researchers and they have captured their attention and imagination. This paper reports on the investigation of a wiki project designed to support university students' collaborative authoring and learning. The design framework of the wiki-based project is outlined and an analysis framework is proposed as the result of combining analysis of students' collaborative actions, e.g. edits and posts in the wiki pages. The framework was applied to investigate students' engagement, their contribution to the wiki content and the patterns of collaboration and content co-creation they followed during the project timeline. Our findings revealed different patterns of students' contribution to their group wiki as well as their different roles. The paper concludes with suggestions for future development of the framework and research in the field of wiki learning design.