Metacognition is a psychological construct that refers to people's knowledge and regulation of their thinking, learning, and problem-solving processes (Brown, 1987; Flavell, 1979). Over the past 35 years, there has been a growing recognition of the importance of metacognition in mathematics learning and performance (e.g., De Corte, Greer, & Verschaffel, 1996; Jacobse & Harskamp, 2012). Indeed, metacognition has been found to have significant effects on mathematics performance both at the elementary and secondary levels (Dignath & Buttner, 2008), and the National Research Council identified metacognition as one of three components central to learning and teaching (Bransford, Brown, & Cocking, 2000). Speaking to the continued importance of metacognition, researchers continue to examine metacognition with regard to mathematics performance (e.g., Jacobse & Harskamp, 2012) and gifted populations (e.g., Hannah & Shore, 2008; Snyder, Nietfeld, & Linnenbrink-Garcia, 2011). Instruments that provide reliable information from which valid inferences about students' metacognitive abilities can be drawn are essential for researchers who study the impact of metacognition on academic achievement and for educators who are responsible for developing and assessing students' metacognitive abilities. When examining the relationships between metacognition and mathematics performance, metacognition is measured in two different ways. In the psychology literature, researchers predominantly use quantitative scales such as self-report questionnaires to measure metacognition (