Urquijo, Silvia PongutáScrivener, Stephen A.R.Palmén, Hilary K.2017-04-152017-04-151993978-94-011-2094-4CSCW systems are invariably intended to support complex group activities. This complexity is reflected in the richness of the data required to adequately evaluate a system inteed to support these activities. Consequently, there is a need for the development of an evaluation technique which can reliably provide disagnostic informatin quickly from rich data (such as video and audio recordings). In this paper, the development and use of an approach based on 'breakdown' within the scope of a Model of Interaction is described. Breakdown analysis provides a systematic means of approaching large quantities of communication data, identifying those areas which highlight problems and relieving the evaluator of the tasks of consulting or becoming an expert in more complex form of conversational analysis or HCI.enText