The importance of space and place in collaborative practices has been strengthened with the ubiquitous computing paradigm, which aims at the integration of computation in physical objects and places. New location-based applications allow users to know where other individuals are in the physical world. New collaborative applications engage users in geographically dispersed and mobile activities. However, there is still a lack of information concerning how mutual location-awareness (i.e. knowing partners' whereabouts) might influence socio-cognitive processes involved in coordination. To address this issue, we conducted field experiments with a mobile and collaborative game, running on Tablet PCs, and compared two interfaces. On the first interface, groups received automatic updates from teammates' whereabouts, while this automatic MLA tool was not provided by the second interface. In addition, all users could use their Tablet PCs to communicate by annotating the map. We found no differences between the two conditions with regard to the task performance. However, contrary to our expectations, players without automatic MLA had a better representation of their partners' paths, wrote more messages and provided more elaborate explanations of their strategies. Additionally, automatic location-awareness undermined the coordination process, leading participants to be less articulate about their strategy. The paper discusses these results and the implications of such results. (C) 2010 Elsevier Ltd. All rights reserved.