We contribute to faultline research by identifying familiarity and cross-subgroup communication as potential moderators in the relationship between diversity faultline and team performance. We employ a novel experimental design utilizing escape rooms as a noninterventional social laboratory, enabling us to capture real-time interactions among 40 teams engaged in problem-solving activities. We find that team familiarity has a negative influence and a suppression effect on success. Faultline affects team success negatively when faultline-induced subgroups do not communicate enough with each other. Our work contributes to a better understanding of complex processes and interdependencies that lead to team success or failure.