A globalizing world increases immigration between nations, raising the question of how acculturation (or its lack) of immigrants and their descendants to host societies affects risk perceptions. A survey of Paterson, New Jersey, residents tested acculturation's associations with attitudes to air pollution and its management, and knowledge of and self-reported behaviors concerning air pollution. Linguistic and temporal proxy measures for acculturation were independent variables along with ethnicity, plus controls for gender, age, education, and income in multivariate analyses. About one-fifth of contrasts between non-Hispanic whites, non-Hispanic blacks, English-interviewed Hispanics, and Spanish-interviewed Hispanics were statistically significant (Bonferroni-corrected) and of medium or higher affect size, with most featuring the Spanish-interviewed Hispanics. Knowledge variables featured the most significant differences. Specifically, Spanish-interviewed Hispanics reported less concern, familiarity with pollution, recognition of high pollution, and vigorous outdoor activity, and greater belief that government overregulates pollution than English-interviewed Hispanics (and than the other two groups on most of these variables too). English-interviewed Hispanics did not differ from non-Hispanic whites, but did on several variables from non-Hispanic blacks. Temporal proxies of acculturation among the foreign-born were far less significant, but concern and familiarity with air pollution increased with time spent in the United States, while belief in overregulation and a positive trend in New Jersey pollution increased with time in the nation of origin. Implications of these acculturation and ethnicity findings for risk perception/communication research and practice are discussed.