This contribution examines the methodological challenges involved in defining the collaborative knowledge-building processes occurring in asynchronous discussion and proposes an approach that could advance understanding of these processes. The written protocols that are available to the analyst provide an exact record of the instructional transactions at a given time in the online discussion. On the basis of a study of online discussion forums used in a higher education context, a model for the analysis of collaborative knowledge building in asynchronous discussion is presented. The model allows examination of the communication from the multiple perspectives of interaction, cognition and discourse analysis. The investigation was conducted using a qualitative case study approach and involved an in-depth examination of three cases. Content analysis of the discourse was done at a number of levels, focusing on the discussion forum itself, the discussion threads, the messages, and the exchanges and moves among the messages. As a result of correspondences found among the variables representing the different levels of the analysis, the most important being the relationship between type of interaction, phase of critical inquiry, and move in the exchange structure, it was possible to build a scheme for assessing knowledge building in asynchronous discussion groups. The scheme integrates the interactive, cognitive and discourse dimensions in computer-supported collaborative learning (CSCL). The study represents a merging of quantitative analysis within qualitative methodology and provides both an analytic and a holistic perspective on CSCL.