During a series of recent natural catastrophes, social media has played an increasingly prominent and varied role in crisis response, ranging from facilitating the recruitment of volunteers during an earthquake to supporting spiritual recovery after a hurricane. In this paper, we propose that social media, beyond the conventional role of information support, can also function as boundary objects, which are crucial in spanning the boundaries among involved parties that inherently restrict crisis response. Using the 2011 Thailand floods as a case study, we present a conceptual model of the role of social media in enabling a coordinated response to disasters. More specifically, the model presents three distinct processes of emergence and the corresponding boundary objects enabled by the use of social media, which are important in bridging the cognitive, relational and social boundaries among the various entities involved in crisis response.