Conceptual frameworks in health care do not address mechanisms whereby teamwork processes affect quality of care. We seek to fill this gap by applying a framework of teamwork processes to compare different patterns of primary care performance over time. We thematically analyzed 114 primary care staff interviews across 17 primary care clinics. We purposefully selected clinics using diabetes quality of care over 3 years using four categories: consistently high, improving, worsening, and consistently low. Analyses compared participant responses within and between performance categories. Differences were observed among performance categories for action processes (monitoring progress and coordination), transition processes (goal specification and strategy formulation), and interpersonal processes (conflict management and affect management). Analyses also revealed emergent concepts related to psychological and organizational context that were reported to affect team processes. This study is a first step toward a comprehensive model of how teamwork processes might affect quality of care.