The concept of Distributed Situation Awareness (DSA) is currently receiving increasing attention from the human factors community. Despite this, some researchers argue that theory and methods for representing SA in collaborative systems are lacking. This article describes a DSA approach to viewing SA in collaborative systems and outlines the propositional network method, a new methodology for evaluating and representing DSA. To demonstrate, examples taken from a recent case study on DSA in multinational warfare operations are presented. The findings are discussed in relation to their implications for DSA during the multinational operations observed, including the structure of DSA in terms of the usage of knowledge by the different agents involved, the distribution and sharing of knowledge between agents, and the salience of the different knowledge items identified.