In a sample of 60 branches of a bank, we examine the influence of age-based faultlines on team performance. Specifically, we propose a model with four mediational paths in the age-based faultline-team performance link. Using a time-lagged design with three data-collection points, we found that task conflict, team reflexivity, and negative team mood mediated the negative relationship between age-based faultline strength and team performance. The results reveal the value of examining different mediational paths to explain the negative impact of teams’ demographic faultlines on team performance, and the need to integrate both task-related and affective aspects of team work in order to improve our understanding about how the influence of team faultlines develops. Furthermore, our findings offer managers practical guidance for reducing faultline effects on team performance.