Recent events have brought increased attention to the possibility and dangers of a radiological terrorist threat and its potential implication on the national capacity for radiation accident preparedness. In such an event, there is a pressing need to rapidly identify severely irradiated individuals who require prompt medical attention from those who have not been exposed or have been subject to low doses. Initial dose assessment is a key component in rapid triage and treatment, however, the development of accurate methods for rapid dose assessment remains a challenge. In this report, the authors describe a recent workshop supported by the Chemical, Biological, Radiological-Nuclear and Explosives Research and Technology Initiative regarding the international effort to increase biological dosimetry capacity to effectively mount an emergency response in a mass casualty situation. Specifically, the focus of the workshop was on the current state of biological dosimetry capabilities and capacities in North America, recent developments towards increasing throughput for biological dosimetry and to identify opportunities for developing a North American Biological Dosimetry Network and forming partnerships and collaborations within Canada and the USA.