The investigation of IT adoption and diffusion in organisations is a core topic of the IS discipline. However, orthodox theories take a mostly rationalist view that treats adoption as a decision situation. In this paper, we aim to show that it is necessary to appreciate the process nature of taking new technology into organisational contexts, and the open-ended nature of this process in terms of social sense-making about the new technology. At the same time, as more and more organisations let social media be part of work and communication practices, understanding what happens when individuals begin to experiment with and participate in these new mediums is increasingly important. Against this backdrop, we present the findings of an in-depth data analysis of enterprise-based short message communications shared across the Yammer enterprise social network at international service consultancy Capgemini. We focus on appropriation-related communication in the first nine months of uptake. By undertaking a time-trend analysis we identify the essential phases in which sense-making and appropriation take place as Yammer is enrolled into Capgemini practices. Our study makes an important contribution toward understanding the processes of technology appropriation in general and sense-making in social media in particular.