Evidence strongly suggests that public health communication campaigns can succeed in changing health-related cognitions and behaviors. For many evaluation studies, however, inferences of campaign effects are only valid to the extent that measures of campaign exposure are themselves valid. This study compares the validity of "aided" and "confirmed" ad recall measures in the context of a statewide tobacco countermarketing campaign using data from the Florida Anti-Tobacco Media Evaluation (FAME) surveys. Both aided and confirmed ad recall measures exhibited positive associations with cumulative gross ratings points (GRPs), a measure of the relative availability of specific countermarketing ads on broadcast television. In addition, both recall measures were significant predictors of campaign-targeted beliefs. Confirmed ad recall, however, was not a significantly better predictor of cumulative GRPs or campaign-targeted beliefs than aided ad recall, and the magnitude of association between both recall measures and targeted beliefs was quite small. These findings raise questions about the marginal utility of confirmed ad recall measures, compared with aided ad recall, in public health communication campaign evaluations. Nevertheless, results do provide evidence that both aided and confirmed ad recall measures are valid measures of campaign exposure.