An ecological-cognitive framework of analysis and a model-tracing architecture are presented and used in the analysis of data recorded from users browsing a large document collection. The users interacted with the Scatter/Gather browser, which clusters documents into groups of similar content and presents users with summaries of cluster content. Predictions made by a computational model of navigation and information foraging are matched against the observed activity. Keywords Information foraging, information scent, cognitive modeling, model-tracing, ACT-R, Scatter/Gather