Alongside citizens’ belief in the legitimacy of democracy, public support for the political regime is crucial to the survival of (democratic) political systems. Yet, we know fairly little about the relationship between citizens’ democratic knowledge and their evaluation of democratic performance from a global comparative perspective. In this article, we argue that the cognitive ability of citizens to distinguish between democratic and authoritarian characteristics constitutes the individual yardstick for assessing democracy in practice. Furthermore, we expect that the effect of citizens’ democratic knowledge on their evaluation of democratic performance is moderated by the institutional level of democracy. We test these assumptions by combining data from the sixth and seventh wave of the World Values Survey and the third pre-release of the European Values Study 2017, resulting in 114 representative samples from 80 countries with 128,127 respondents. Applying multilevel regression modeling, we find that the higher a country’s level of democracy, the more positive the effect of democratic knowledge on citizens’ assessment of democratic performance. In contrast, we find that the lower the level of democracy in a country, the more negative the effect of citizens’ democratic knowledge on their evaluation of democracy. Thus, this study shows that citizens who are more knowledgeable about democracy are most cognitively able to assess the level of democracy in line with country-level measures of democracy. These results open up new theoretical and empirical perspectives for related research on support for and satisfaction with democracy as well as research on democratization.