Research on learning suggests the importance of helping students organize their knowledge around meaningful patterns of information. This paper reports on a multi-institutional study to investigate how senior computer science majors articulate and organize their knowledge of programming concepts using a cardsorting technique adopted from knowledge acquisition. We show that card-sorts are an effective means of eliciting students’ knowledge structures and suggest they can also be used to help students organize their knowledge throughout the curriculum. Categories and Subject Descriptors K.3.2 [Computer and Information Science Education]: Computer Science Education – computer science education research. General Terms Experimentation. Keywords Content analysis, Card sort, Knowledge, Expertise.