Theoretically, reflection is known to be an essential skill for improving learning on a metacognitive level. In practice, students may not use it of their own accord to improve this kind of learning because it can be mentally demanding. The author reports on the legitimation of an instrument measuring self-induced self-reflective thinking, which is reflection of one's own accord focused on improving general knowledge of the learning process. In 2 studies, the psychometric properties and nomological validity of open-ended self-induced self-reflective thinking questions were examined. Senior high school students responded to these questions and several measures of general knowledge of the learning process. Results showed statistically significant relationships between self-induced self-reflective thinking and general knowledge of the learning process. Implications for educational research are discussed.