The importance of metacognition in modeling processes is not questioned in the international discussion on modeling. However, in contrast to the assumed importance, a relatively small number of studies were conducted focusing metacognition in modeling. One of the reasons may be the fact that metacognition is a rather vague concept developed in different domains and with different conceptualizations. Another reason could be challenges in measuring metacognition. In this article, we will first present concepts of metacognition, which are used by the studies presented afterwards. In addition, we will describe different methods and instruments for measuring students’ metacognition concerning modeling as well as important research results. We will close with a summary and open research questions as well as a description of a study that tries to tackle some of these open questions.