The primary goal of this study was to explore the changes that four Korean university students made in their regulation of cognition during reading processes. The students were trained using explicit reading strategy instruction based on the CALLA model. To this end, first, metacognition was framed and categorized by the definition from Baker and Brown (1984) and, second, a scoring scale for measuring the readers' regulation of cognition was developed based on the study by Block (1992) to examine and trace any changes in their regulation processes. For data analyses, the participants' think-aloud protocols were used. The results indicate that there were marked changes in the frequencies of their regulation processes over time. Specifically, the students' overt strategic and regulatory behaviors in a regulation process showed more flexibility and organization toward the end of the strategy training. This study suggests that students would benefit from being provided with sufficient time for practice in order to build effective regulation of cognition in reading processes and that the teacher should understand the complex nature of the regulation processes that students go through. In addition, think-aloud procedures as an instructional tool for effective strategy training was shown to be a worthwhile technique in the classroom.