The maldistribution of political knowledge in society has important consequences for individual-level political behavior and the representativeness of governmental policies. Increased media selectivity threatens to widen the gap between the politically well-informed and the less-informed by decreasing chance encounters with incidental political information. This study asks: Does exposure to incidental political information through social media promote political learning among users? We conduct two longitudinal, controlled experiments administered through the Facebook platform, and find no statistical difference in the levels of factual political knowledge among participants exposed to political information compared to those who were not. However, those in the treatment group with low political interest may be more likely to venture an incorrect guess than those in the control group, suggesting that exposure to incidental political information through social media may lead to an increase in self-perceived knowledge among some.