To describe public perceptions on breastfeeding constraints, the authors studied the responses of 2369 US adults who participated in the Healthstyles 2000 national mail survey (response rate = 75%). Among them, 2351 answered at least 1 of the 12 breastfeeding items. Public perceptions were positive for 8 of the 12 items. Among the other 4, however, almost half of US adults (45%) agreed that a breastfeeding mother has to give up too many lifestyle habits, 31% thought that babies ought to be fed cereal or baby food by age 3 months, 31% said that 1-year-olds should not be breastfed, and 27% considered breastfeeding in public embarrassing. The results revealed more negative perceptions among non-whites, people under 30 or above 65 years, and those who had low income and less education. To promote and support breastfeeding in society as a whole, these messages need to be considered in planning and implementing breastfeeding interventions.