The quality of communication between patients and clinicians can have a major impact on health outcomes, and limited English proficiency can interfere with effective communication. More than ten million U.S. residents speak English poorly or not at all, constituting a language chasm in the health care system. This paper reviews the evidence on the link between linguistic competence and health care quality and the impact of particular language-assistance strategies. Drawing on the experiences of fourteen health plans that have been at the forefront of linguistic competence efforts, we identify lessons for plans, purchasers, policymakers, and researchers on ways to improve the availability and quality of interpreter services.