Increasing information flow often leads to widening gaps in knowledge between different socioeconomic status (SES) groups as higher SES groups are more likely to acquire this new information at a faster rate than lower SES groups. These gaps in knowledge may offer a partial but robust explanation for differential risk behaviors and health disparities between different social groups. Drawing on the Health Information National Trends Survey (HINTS 2003), a national survey of communication behaviors conducted by the National Cancer Institute (NCI), we examine the relationship between publicity and knowledge gaps on two cancer topics that received different levels of publicity: knowledge about tobacco and sun exposure and their respective links to cancer. Analyses of the HINTS 2003 data suggest that differential knowledge levels of causes of cancer between SES groups are one potential explanation of cancer disparities that have been extensively reported in the literature. It is evident that high income and high education are associated with awareness about causes of major cancers such as lung and skin, and may allow people to protect themselves and minimize their risks. The data also show that heavier media attention could attenuate the knowledge gaps though moderate publicity or lack of news coverage may actually widen them. Last, the findings in this article suggest that it is necessary to take into account the SES variation within different racial and ethnic groups rather than mask them by treating the groups as one.