Studying texts constitutes a significant part of student learning in health professions education. Key to learning from text is the ability to effectively monitor one's own cognitive performance and take appropriate regulatory steps for improvement. Inferential cues generated during a learning experience typically guide this monitoring process. It has been shown that interventions to assist learners in using comprehension cues improve their monitoring accuracy. One such intervention is having learners to complete a diagram. Little is known, however, about how learners use cues to shape their monitoring judgments. In addition, previous research has not examined the difference in cue use between categories of learners, such as good and poor monitors. This study explored the types and patterns of cues used by participants after being subjected to a diagram completion task prior to their prediction of performance (PoP). Participants' thought processes were studied by means of a think-aloud method during diagram completion and the subsequent PoP. Results suggest that relying on comprehension-specific cues may lead to a better PoP. Poor monitors relied on multiple cue types and failed to use available cues appropriately. They gave more incorrect responses and made commission errors in the diagram, which likely led to their overconfidence. Good monitors, on the other hand, utilized cues that are predictive of learning from the diagram completion task and seemed to have relied on comprehension cues for their PoP. However, they tended to be cautious in their judgement, which probably made them underestimate themselves. These observations contribute to the current understanding of the use and effectiveness of diagram completion as a cue-prompt intervention and provide direction for future research in enhancing monitoring accuracy.