We propose a data-based approach to doing ethnographic research in a digital environment. It has three main components. First, it treats online conversational environments as human communities that ethnographers can engage with as they would in onsite fieldwork. Second, it represents those conversations and the fieldnotes made by researchers thereon in network form. e call these networks semantic social networks, as they incorporate information on social interaction and their meaning. They encode a map of the associations between key concepts as perceived by informants as a group. Third, it uses methods borrowed from network science to process these data. We present an application of this method to a large online conversation about community provision of health and social care, and discuss its potential for harnessing collective intelligence.