Through the lens of 'communities of practice' (Wenger, 2000) we examined decision-making boundaries and tensions in multiagency settings. Sixteen semi-structured interviews were conducted with operational decision makers from services across Australia. Data analysis was contextual and narrative, focusing on meanings signifying cultures and practices. Results indicate that protocols and guidelines which provide boundaries for a community of practice, could at times become an obstacle. Participants reported difficulties in sharing a 'common level of understanding' and 'getting the bigger picture'. The strongest theme was the importance placed on building relationships between services prior to emergency events. We found capability of multiagency decision making is enhanced when informal multiagency networks are already in place. These networks contribute to building a shared understanding. We propose that multiagency communities of practice could be enhanced if services increased their level of formal multiagency engagement and promoted the informal multiagency networking of their members and teams.