Situation awareness (SA) continues to receive a considerable amount of attention from the ergonomics community given that need for operators to maintain SA is frequently cited as a key to effective and efficient performance. Although complex and dynamic environments such as that of a main control room (MCR) in a nuclear power plant (NPP) are operated by operation teams, and while team situation awareness (TSA) is also cited as an important factor, research is limited to individual SA. However, understanding TSA can provide a window onto the characteristics of team acquisition as well as the performance of a complex skill. Therefore, such knowledge can be valuable in diagnosing team performance successes and failures. Moreover, training and design interventions can target the cognitive underpinnings of team performance, with implications for the design of technological aids to improve team performance. Despite these advantages and the importance of understanding TSA, measures and methods targeting TSA are sparse and fail to address it properly. In this study, an objective TSA measurement method is developed in an effort to understand TSA. First, key considerations for developing a method are derived. Based on these considerations, the proposed method is developed while mainly focusing on the creation of logical connections between team communications and TSA. A speech act coding scheme is also implemented to analyze team communications. The TSA measurement method developed in this study provides a measure for each level of TSA. It was revealed from a preliminary study that this TSA measurement method is feasible for measuring TSA to a fair extent. Useful insight into TSA is also derived. (C) 2011 Elsevier Ltd. All rights reserved.