This thesis combines theories from cross-cultural psychology with literature on group faultlines to understand cultural barriers to communication and cooperation experienced in multinational emergency management teams. The aim is to investigate whether the faultline concept is a viable theoretical vocabulary for addressing cultural differences in communication and cooperation (in the domain of emergency management). Culture is defined as a relatively organized system of shared meanings which influences people’s cognition, values, behaviors, and so on. Group faultlines are hypothetical dividing lines that may split a team into homogeneous subgroups based on demographic characteristics. Three papers are included in the thesis, all of which investigate various aspects of group behavior in relation to emergency management. Results suggest that faultlines can be formed not only by demographic characteristics, but also by culturally-driven behavior. The results presented in the papers and in this thesis are meant to supply emergency management personnel with general knowledge of cultural differences and ideas for future ‘cultural awareness’ training. The thesis contributes to the scientific community by taking cross-cultural research into the applied domain so that its findings can be made relevant to people in multinational organizations.