Examining the relationships among social motivations, media use, and levels of political knowledge, a study (1) measured the unique contribution of social motivations beyond simple exposure and individual motivations, (2) tested for interactions between social and individual motivations and public affairs exposure, and (3) examined the interactive relationships among the variables. Telephone interviews with 737 adults determined the perceived influence of mass media exposure on family, friends, and co-workers. These three social motivation types allowed the relationship between individual media patterns and the possible social motivations for those patterns to be examined. Findings showed that, although traditional individual level predictors were a significant influence, social level predictors should be taken into account when an individual's knowledge levels are being considered. Group interactions provided a significant control for all other variables. Results also indicated that the relationship between social and individual motivations is substantially additive and that public affairs exposure interacts with social influences. In addition, while increased public affairs exposure showed no corresponding increase in knowledge, findings showed that the media were able to transfer substantial amounts of information at lower motivation levels. Motivation, then, was the overall best predictor of knowledge. (Supplementary tables and appendixes are included.) (JD)