This report provides both summaries and detailed discussions of the theoretical foundations, methods, and findings of empirical research aimed at identifying barriers to collaborative decision-making in multicultural On-Site Operations Coordination Centers (OSOCC). The research was conducted in 2005 and 2006 at Linköping University and Högskolan i Skövde and was sponsored by the International Department of the Swedish Rescue Services Agency. The experiments were controlled but dynamic laboratory studies of communication, collaboration, and decision making by culturally homogeneous teams of four that were assembled ad-hoc and on-site. The teams- task was to manage and conduct emergency operations within the C3Fire microworld. C3Fire recorded all communication among team members and all the actions they took. Participants individually completed a battery of self-report instruments about their values and beliefs. Results are summarized in a list of 30 dimensions of demographic and cultural diversity that are likely to be found whenever small multinational teams are formed ad-hoc and on-site. The potential impact of these dimensions is explained using the analogy of faultlines. Alignments of dimensions of diversity have the potential to generate friction and split a team into subgroups. Activated faultlines are barriers to communication, collaboration, and decision making. The report concludes with discussions of the implications of group faultlines and dimensions of cultural diversity for the SRSA-s training programs for OSOCC personnel, for the Swedish society, and for the scientific community.