The knowledge gap hypothesis predicts that information inequity will be amplified rather than attenuated by the media. Previous research has focused on the role of mass media exposure and has not examined the roles of social media and social networks in mitigating the gap. This study investigated the potential moderating roles of social media engagement, social networks, and the interaction between engagement and online and offline networks. Hypotheses were tested with data from a national sample survey ( N = 991) concerning political and health knowledge. More social media engagement predicted a smaller knowledge gap in the political domain but not the health domain. More diverse and denser social media networks predicted a smaller political, but not health, knowledge gap. Social media engagement interacted with mixed-media relationships to predict the political knowledge gap. More engagement with mixed-media relationships was associated with a smaller political knowledge gap.