This analysis examines knowledge of HIV and AIDS among 71,370 persons interviewed in a national sample of the U.S. population.

Factor analysis of 26 questions about HIV infection and AIDS identified four distinct dimensions of AIDS knowledge : 1) transmission mechanisms ; 2) commonly known nontechnical information ; 3) definitions of AIDS ; and 4) technical information.

Significant differences across racial, ethnic, socioeconomic, and demographic groups exist for each dimension of AIDS knowledge.

In general, racial minorities and those with lower socioeconomic status are shown to have lower knowledge levels.

Exposure to mass media about AIDS, and knowing a person with HIV or AIDS, are also strong predictors of increased knowledge.

Multivariate analysis demonstrates 1) that socioeconomic status is a better predictor of knowledge of AIDS than race or ethnicity ; and 2) exposure to AIDS mass media has the strongest effect on all dimensions of AIDS knowledge except for knowledge of technical issues about AIDS.

Policy implications of these results are discussed.