The relationship between acculturation and smoking behavior was examined in four Asian-American groups that included recent immigrants and US-born Koreans, Chinese, Vietnamese and Cambodians residing in the Delaware Valley of Pennsylvania and New Jersey. The study was part of a community-based, comprehensive cross-sectional study designed to assess a broad array of knowledge, attitudes and behaviors on tobacco use and tobacco-related cancer issues in the target multi-ethnic and multi-lingual Asian-American community. The sample of 1374 respondents was selected using a stratified-cluster proportional sampling technique, with a response rate of 83%. Findings indicated that acculturation had a variable effect on smoking behavior: more acculturated youth and less acculturated male adults had higher smoking rates than the less acculturated youth and the more acculturated male adults. Smoking rates for all females were generally lower than those of males regardless of acculturation status; however, acculturated adult females had a higher smoking rate than the less acculturated. (Contains 2 tables.)