Insights into the process of mathematical problem posing is a central concern in mathematics education research. However, little is known about regulative or metacognitive behaviors that are essential to understanding this process. In this study, we investigate metacognitive behavior in problem posing. We aim at (1) identifying problem-posing-specific metacognitive behaviors and (2) applying these identified metacognitive behaviors to illustrate differences in problem-posing processes. For these aims, we identified problem-posing-specific metacognitive behaviors of "planning," "monitoring & control," and "evaluating" in task-based interviews with primary and secondary pre-service teachers. As a proof of concept, the identified behaviors are applied on two selected transcript fragments to illustrate how a problem-posing-specific framework of metacognitive behavior reveals differences in problem-posing processes.