Decades of research have confirmed that debates increase viewer knowledge about the issue stands of the candidates. However, the conditions under which viewers learn are less well understood. In this article, we examine how differences in the context of information in presidential debates affect both who learns from such debates and what they learn. Consistent with previous literature, we report that watching the debates increased knowledge of campaign issues and related matters discussed in the debates. We also found that knowledge based on accurate information that was uncontested in the debate was gained at a greater rate than knowledge based on information that was presented by one candidate but contested by the other. And consistent with confirmation bias, learning based on information that was contested in the debate was influenced by viewers’ candidate preferences more often than not.