Research has invested a great deal of effort to explain how individuals' behaviors are affected by job demands and how job resources may assist them in upholding motivation and engagement. However, how employees working in teams may still successfully contribute to teamwork under demanding conditions needs further consideration. Thus, in extending the job demands-resources (JD-R) model to the team level, I build theory on team demands (i.e., constraints) and team resources (i.e., diversity) to interact in predicting team member behavior. Drawing on a multi-informant cross-level research design with data from innovation teams, I use hierarchical linear modeling (HLM) to test the hypotheses. Although my results lack support for the curvilinear relationship of team demands with individual behavior derived from activation theory, I find reversed cross-level interaction effects of team demands with job-related (i.e., skills) team diversity compared to job-unrelated (i.e., age) team diversity. As such, I show team members to be more motivated and engaged in teams of either high skill diversity or low age diversity. These findings show that team diversity needs to be dealt with conscientiously. I discuss respective implications for research and practice on how to balance diversity within innovation teams.