This study examined the relationship between socioeconomic status (SES) and environmental tobacco smoke (ETS) exposure among non-smoking females, determined which SES variable(s) were most strongly associated with ETS exposure, and examined whether the relationship between SES and ETS exposure was the same for Blacks and Whites. Participants were 404 never-smoker females recruited in the community. Independent variables included income, education, occupation, median income within zip code of participants' residence, and ethnicity. Number of days per week exposed to ETS in the past year was the dependent variable. There was a significant correlation between CO levels (parts per million, ppm) and self-reported ETS exposure (r = 0.22, p<0.001). The mean CO level exposure was 1.81±1.19 ppm, and the mean number of days per week of ETS exposure was 4.72±4.71. The most frequent source of ETS exposure was at public places (64.4%). Although Blacks tended to report higher ETS exposure than Whites (p = 0.08), this tendency disappeared when SES indicators were entered in the model. Correlations among SES indicators were either non-significant or very modest suggesting that different SES indicators may not measure the same construct. Education was the only SES variable that was significantly associated with ETS exposure in this population. The relationship between SES and ETS exposure was similar for both Blacks and Whites. These findings suggest that education may be the most important factor to be considered when designing interventions to decrease ETS exposure among young non-smoking females (e.g., public education of the hazards of ETS exposure and awareness of existing tobacco-control laws and regulations). © 2000 Society for Research on Nicotine and Tobacco.