This study tests an expanded Structural Influence Model (SIM) to gain a greater understanding of the social and cognitive factors that contribute to disparities in cancer risk knowledge and information seeking. At the core of this expansion is the planned risk information seeking model (PRISM). This study employed an online sample (N = 1,007) of African American, Hispanic, and non-Hispanic White adults. The addition of four cognitive predictors to the SIM substantially increased variance explained in cancer risk knowledge (R(2) = .29) and information seeking (R(2) = .56). Health literacy mediated the effects of social determinants (socioeconomic status [SES] and race/ethnicity) on cancer risk knowledge, while subjective norms mediated their effects on cancer risk information seeking. Social capital and perceived seeking control were also shown to be important mediators of the relationships between SES and cancer communication outcomes. Our results illustrate the social and cognitive mechanisms by which social determinants impact cancer communication outcomes, as well as several points of intervention to reduce communication disparities.