The article discusses AIDS knowledge in detail to determine 1) the general level and distribution of AIDS knowledge among the U.S. population; 2) the psychometric properties of standard AIDS knowledge questions; and 3) the factors, including AIDS mass media exposure, which predict increased knowledge about AIDS. To investigate the issues outlined above data from the National Health Interview Survey (NHIS) is utilized. The "AIDS definition" and "technical" questions are both related to issues that are not commonly communicated in AIDS intervention efforts. Race was a strong significant predictor of knowledge across all dimensions of the scales. These findings indicate the there are great variations in AIDS knowledge levels among the U.S. population, with significant differences in AIDS knowledge across racial, ethnic, socioeconomic, and demographic groups. Moreover, the very strong effect of AIDS mass media exposure indicates that public health efforts at increasing knowledge levels related to AIDS have had a significant impact on AIDS knowledge. The results of this analysis indicate that a great opportunity exists for AIDS educators to use mass media to educate the public about AIDS, and that there are certain populations, such as non-whites, Hispanics, and the poor who need targeted AIDS educational efforts.