The rapid pace of social media means that our understanding of the way in which it facilitates the learning process continues to lag. The findings of a longitudinal study of an executive MBA cohort over a period of eight months in their use of the social media application Yammer is presented. Student interaction data was analysed using a form of thematic analysis termed genre analysis (Westman & Freund, 2010) to categorize the various interactions observed. The major data source used to inform this study was a textual analysis of the Yammer user traffic of an executive MBA cohort. Consistent with user behaviour outside of a university context students tended to adapt Yammer to suit their own needs, utilising the tool in a variety of diverse ways over an extended period to support their learning and cohort interactions. Over time the ownership and use of the Yammer site shifted to become student driven and facilitated. The motivations behind the site's use, perceived advantages and disadvantages and changes in usage patterns are documented. The case provides a useful insight into the way in which students used this technology to facilitate their learning goals and how patterns of behaviour changed over time in response to the changing needs of the cohort.