Diversity faultline strength – the extent to which diversity attributes within a group converge in such a way that they split a group into homogeneous subgroups – can decrease group performance. Based on the categorization–elaboration model (CEM) of workgroup diversity, we assumed that task motivation can overcome the detrimental effects of faultlines. We further assumed that this effect is contingent on the groups' diversity beliefs and that it is mediated by the elaboration of task-relevant information. Forty-three student groups worked on a computer-simulated complex problem solving scenario. The group faultline strength was calculated over the attributes gender, age and educational background. Information elaboration was elicited by means of behavioural coding. Results revealed a three-way interaction of faultline strength, diversity beliefs and task motivation: groups overcame the detrimental effects of faultlines only if they exhibited pro-diversity beliefs and high task motivation. The three-way interaction of faultline strength, diversity beliefs and task motivation was partly mediated by information elaboration. Practical and theoretic implications are discussed.