This research-in-progress aims at investigating what moderating effects use of Agile Software Development (ASD) methods and practices has on negative performance effects of faultlines, i.e. specific configurations of attributes in team members. Based on literature in ASD and psychology, a model of the moderating effects of ASD practices is developed and is to be assessed using a global online study. Since ASD practices shape team work and can be linked to known moderators of negative faultline effects, we expect to find moderating effects of ASD methods and practices on faultline effects. Information on the prevalence and moderation of faultline effects in ASD teams will help with a more detailed understanding of how ASD practices work and the contingencies that can inhibit or support their positive effects. Insights into group functioning in ASD settings will provide guidance on which ASD practices can help with negative team dynamics.