This thesis explores how cognitive artefacts contribute to the process of reaching common ground within collaborative groups through a study of both Clark's theory of Common Ground and of how artefacts are understood to be used, both by individuals and as seen in distributed cognition. This was accompanied by an ethno-methodologically inspired study in the natural setting of a kitchen to observe how artefacts are used when negotiationg common ground. After the study's completion, participants were interviewed in order to establish whether common ground was successfully established ant to look for consistency between obeservations from the study and how the participants motivate their actions. The study was analysed in order to find patterns, of which four distinct kinds were indentified; these categories were then related to facts established in the study of Common Ground and artefacts.