Metacognition is one of the most widely studied constructs in contemporary psychological research in educational, instructional, and developmental psychology. Despite numerous attempts to define the construct of metacognition, agreement on how best to delimit it remains elusive (Hacker, Dunlosky, & Graesser, 1998; Tobias & Everson, 2000a). Nevertheless, the flood of research on metacognition over the past quarter century, both in the United States and elsewhere, suggests that murky definitions have not deterred investigators working in these fields. Earlier reviews of the literature on metacognition (see, for example, Metcalfe & Shimamura, 1994; Hacker et al., 1998) suggest that despite disagreement about its definition, metacognition is assessed typically from inferences based largely on observations of students’ performance, or through interviews with students, or via self-report measures (Schraw & Impara, 2000). Thus, it appears that the method of observation defines the construct, that is, metacognition is the data from a metacognitive self-report inventory or from an observational protocol.