Prior studies comparing US-born and foreign-born Asian Americans have shown that birth in the US conveys greater risk of obesity. Our study investigates whether retention of Asian culture might be protective for obesity despite acculturation to US lifestyle. We classified self-identified Asian American respondents of the California Health Interview Survey as traditional, bicultural, and acculturated using nativity and language proficiency in English and Asian language. We then examined the association of acculturation with overweight/obesity (BMI ≥ 25 kg/m²) in a multivariate regression model. Acculturated respondents had higher adjusted odds of being overweight/obese than bicultural respondents (2.13 [1.40-3.23] for men, 3.28 [2.14-5.04] for women), but bicultural respondents had similar odds of being overweight/obese as traditional respondents (.98 [.69-1.41] for men, .72 [.50-1.05] for women). Among the bicultural, second and first generation respondents were equally likely to be overweight/obese. Biculturalism in Asian Americans as measured by Asian language retention appears protective against obesity. Further research is needed to understand the mechanisms underlying this association.