Bilingual immigrants appear to have a health advantage, and identifying the mechanisms responsible for this is of increasing interest to scholars and policy makers in the United States. Utilizing the National Latino and Asian American Study (NLAAS; n = 3,264), we investigate the associations between English and native-language proficiency and usage and self-rated health for Asian and Latino U.S. immigrants from China, the Philippines, Vietnam, Mexico, Cuba, and Puerto Rico. The findings demonstrate that across immigrant ethnic groups, being bilingual is associated with better self-rated physical and mental health relative to being proficient in only English or only a native language, and moreover, these associations are partially mediated by socioeconomic status and family support but not by acculturation, stress and discrimination, or health access and behaviors.