OBJECTIVE: This study examines (a) providers' and interpreters' perception of their competition in controlling the content and process of provider-patient interactions, and (b) the challenges to providers' and interpreters' collaboration in bilingual health care. METHODS: I recruited 26 professional medical interpreters from 17 languages and 39 providers from 5 specialties to participate in in-depth interviews and focus groups. Grounded theory was used for data analysis to develop themes in areas where providers and interpreters compete and assert their expertise. RESULTS: Providers and interpreters experience conflicts over their expertise and authority due to their practice in (a) adopting different speech conventions, (b) controlling the other's narratives, and (c) overstepping expertise and role boundaries. CONCLUSION: A successful bilingual medical encounter is dependent on the interpreters' and providers' ability (a) to understand, communicate, and negotiate their and others' communicative strategies/goals and (b) be adaptive of and responsive to others' management of the communicative process. PRACTICE IMPLICATIONS: Authority in bilingual health care should not be established through pre-existing categories or expertise but negotiated and coordinated during the interactive process, which would allow individuals to be adaptive to the issues emerged in the communicative process.