In recent years, more and more researchers have been investigating cognitive and metacognitive skills that seem to be related to the improvement of the performance of kindergarten children. In this paper, we present the cognitive processes that are related to it, such as working memory, attention, inhibitory control, executive function, and processing speed. In addition, we refer to metacognitive skills and their role in controlling and regulating cognitive processes in order to improve children’s performance. Finally, we present a new taxonomy of skills, the pyramid of 8 levels, as well as their gradual development through the appropriate cognitive and metacognitive mechanisms. In this study, a holistic and multi-disciplinary approach is attempted by collecting and utilizing data from sciences such as cognitive psychology, neuropsychology, and philosophy. The research has led us to the 8 layers that underpin metacognition in preschoolers following the model of the hierarchical organization of knowledge.