This study explores the intersection of media use, political discussion, and exposure to political difference through a focus on how Internet use might affect the overall heterogeneity of people’s political discussion networks. Advanced and tested herein is the inadvertency thesis, which theorizes that limitations of selective exposure processes combined with weakened social boundaries found in the online environment suggest that people may be exposed to at least some additional political difference online, if only inadvertently. Hierarchical regression and mediation analyses confirm that online political discussion (directly) and online news (directly and indirectly) bear small yet significant relationships to the overall heterogeneity of political discussion networks, and that partisanship moderates the relationship between online political discussion and political discussion network heterogeneity.