Teamwork is challenging in cooperative digital games, especially between strangers. In many online cooperative games, teams have a short-lived existence and ever-changing membership. Our study explores how short-lived ad hoc teams of strangers communicate and investigate its effect on team performance. We analysed 2256 text message instances produced by teams during a 45-minute interaction. Our findings show that team communication is negatively related to performance, and affects performance over and beyond prior experience. A content analysis shows that teams generally have higher task-related communication than socio-emotional communication. This pattern is consistent throughout the duration of the interaction period. The results are disc...