Much misinformation and many falsehoods related to politics circulate online. This paper investigates how youth judge the accuracy of truth claims tied to controversial public issues. In an experiment embedded within a nationally representative survey of youth ages 15-27 (N=2,101), we examined factors that influenced youth judgements regarding the accuracy of the content. Consistent with research on motivated reasoning, youth assessments depended on a) the alignment of the claim with their prior policy position and, to a lesser extent, on b) whether the post included an inaccurate statement. However, and most importantly, among those participants who reported the most media literacy learning experiences, there was a large, statistically significant difference in ratings of accuracy between those exposed to a post that employed misinformation and those who saw an evidence-based post. Implications for educators and policymakers are discussed.