This article describes a study, which aimed to document the work practice of a team of commanders responding to an emergency, and to identify areas and activities, that may be enhanced by the use of command and control tools. The study was based on a ‘human-in-the-loop’ simulation with emergency management commanders as articipants. Communication analyses – episodic analysis, socio-metric status and communication roles – were used to assess coordination among the commanders. The results indicate that the commanders used informal arrangements within the established command and control structures to perform various informal functions and take on diverse communication roles across organizational and domain boundaries. Cross-domain and cross-organizational knowledge was the most important enabler of this type of coordination. General tools providing methods and aids to indicate and support informal functions and communication roles were identified as absent.