The objective of this study is to examine the association between acculturation and BMI among Asian Americans using multiple measures of acculturation. Data of 847 Chinese, Korean and Vietnamese recruited for a health education program in Maryland during 2009 to 2010 were used. Acculturation was measured by the short version of Suinn-Lew Asian Self-Identity Acculturation Scale (SL-ASIA) and its individual components. Height and weight were measured by trained staff. Multiple linear regressions were used to estimate the association between acculturation and BMI. After adjusting for age, gender, education, income, marital status, and ethnicity, SL-ASIA (β = 0.71, SE = 0.28), having education in the US (β = 0.56, SE = 0.28), younger age of arrival (0-5 years: β = 3.32, SE = 0.76, 6-10 years: β = 1.55, SE = 0.78), self identified as Americans (β = 1.51, SE = 0.77) and equal preference of Asian/American food in restaurants (β = 0.92, SE = 0.28) were significantly associated with increased BMI. The association between acculturation and BMI was stronger among men than women, strongest among Chinese and weakest among Vietnamese. Acculturation was moderately associated with increased BMI among Asian Americans and this association varied by measures of acculturation. The association of acculturation and BMI was moderated by sex and ethnicity groups.