Metacognition is increasingly recognized as important to learning. Research in second language (L2) teaching and learning has shown that learners’ metacognition skills can directly promote achievement in language learning. This article describes the extent to which metacognition facilitates students’ learning achievement. The article begins by establishing a general understanding of the term ‘metacognition’ and then moves on to a discussion of two components of metacognition that directly influence one’s metacognition skills. These two components are metacognitive experience and metacognitive knowledge.