OBJECTIVE: To assess the association of limited English proficiency (LEP) and physician language concordance with patient reports of clinical interactions. METHODS: Cross-sectional survey of 8638 Kaiser Permanente Northern California patients with diabetes. Patient responses were used to define English proficiency and physician language concordance. Quality of clinical interactions was based on 5 questions drawn from validated scales on communication, 2 on trust, and 3 on discrimination. RESULTS: Respondents included 8116 English-proficient and 522 LEP patients. Among LEP patients, 210 were language concordant and 153 were language discordant. In fully adjusted models, LEP patients were more likely than English-proficient patients to report suboptimal interactions on 3 out of 10 outcomes, including 1 communication and 2 discrimination items. In separate analyses, LEP-discordant patients were more likely than English-proficient patients to report suboptimal clinician-patient interactions on 7 out of 10 outcomes, including 2 communication, 2 trust, and 3 discrimination items. In contrast, LEP-concordant patients reported similar interactions to English-proficient patients. CONCLUSIONS: Reports of suboptimal interactions among patients with LEP were more common among those with language-discordant physicians. PRACTICE IMPLICATIONS: Expanding access to language concordant physicians may improve clinical interactions among patients with LEP. Quality and performance assessments should consider physician-patient language concordance.