Coherent, collective understanding (sense) of circumstances and situations is critical to coordinated, and safe action. Especially in process control domains, we may expect that reliable organizations will possess processes that develop, maintain, distribute, and, when necessary, repair this collective understanding. These processes are most likely to be visible to researchers in high tempo, high uncertainty work settings such as hospital intensive care units. Our research has focused on sensemaking. The research demonstrates how workers create and distribute sense within small work groups and also how they use the results of these efforts to make sense during ongoing work activities. Practitioners tradeoff the opportunity costs of formal, collective sensemaking (sensemaking at intervals) against the value that this preparation provides to sensemaking during high tempo work (sensemaking on-the-fly). They adjust their investments in formal sensemaking in response to the work demands. Further study of this dynamic balance will provide insight the ways that experienced practitioners manage flow of attention and construct platforms for managing risks during future, uncertain, high stakes work. High Reliability Organizations are marked by an accurate, precise, and commonly held understanding about current operations and the relationship between those operations and potential accidents. The sensemaking processes create and nourish a common understanding of the current situation among the operators. This is one of the most important conditions for the realization of patient safety.