Successful decision-making critically involves metacognitive processes such as monitoring and control of our decision process. Despite the importance of metacognition for many aspects of life, little is known about how our metacognitive system operates or about what kind of information is used for metacognitive (second-order) judgments. In short, how do we know what we are doing, or how do we know that we know? In this talk, I will discuss the relationship between metacognitive performance and first-order task performance. In one study, we recorded EEG signals while participants were asked to make a “diagnosis” after seeing a sample of fictitious patient data (a complex pattern of colored moving dots of different sizes). Results demonstrate that the information that contributes to first-order decisions differs from the information that supports metacognitive judgments. Further, time frequency analyses of electroencephalographic signals reveal that metacognitive performance is specifically associated with prefrontal theta band activity. In a second study, we explored whether “internal information” contributes differentially to first- and second-order performance. First- and second-order decisions have been strongly linked to the strength of the incoming sensory signal during for instance a visual detection task. However, recently neural activity related to motor preparation and execution has been linked to decision-making and metacognition. Our results demonstrate that, under constant first-order performance, the ability to monitor our decision process dramatically decreases when having no access to neural activity related to motor execution, setting the stage for metacognition as an “embodied” process.