In this study we examined the challenges to providers' and interpreters' collaboration in bilingual health care. We conducted in-depth interviews and focus groups with 26 medical interpreters (speaking 17 languages) and 32 providers (from four specialties) in the United States to provide an empirically based framework of provider-interpreter trust. Constant comparative analysis was used for data analysis. We identified four dimensions of trust, theoretical constructs that can strengthen or compromise provider-interpreter trust: interpreter competence, shared goals, professional boundaries, and established patterns of collaboration. In this article we describe how these dimensions highlight tensions and challenges that are unique in provider-interpreter relationships. We conclude with practical guidelines that can enhance provider-interpreter trust, and propose future research directions in bilingual health care.