Background: Many previous studies of health care teamwork have taken place in clinical teams with high staffing ratios (i.e., high ratios of staff to patients). Purpose: The aim of this study was to identify clinicians' viewpoints of foundational resources necessary to support good team functioning in the context of low staffing ratios. Methodology: We used administrative data, validated with local mental health chiefs, to identify mental health teams that had achieved high team functioning despite low staffing ratios in U.S. Department of Veterans Affairs medical centers. Guided by a recently developed model of team effectiveness, the Team Effectiveness Pyramid, we conducted qualitative interviews with 21 team members across three teams within two medical centers. Interview questions focused on the resources needed to support good team functioning despite low staffing ratios. We used directed content analysis to analyze results. Results: We found there were several domains of relevant resources: material, staffing, temporal, organizational, and psychological. These represent an expansion of the domains originally included in the Team Effectiveness Pyramid. Conclusions: Within the five domains, we identified key tensions to be addressed when forming teams, including the balances between providing care for new versus established patients, emphasizing shared caseloads within the team versus matching patients to clinicians based on individual expertise, and establishing reporting structures by clinical discipline versus team membership. Practice Implications: Establishing high-functioning health care teams in the context of low staffing ratios requires attention to key resource domains and fundamental trade-offs in how teams are structured.