In self-paced learning, when the regulation of study effort is goal driven (e.g., allocated to different items according to their relative importance), judgments of learning (JOLs) increase with study time. When regulation is data driven (e.g., determined by the ease of committing the item to memory), JOLs decrease with study time (Koriat, Ma'ayan, & Nussinson, 2006). We induced learners to interpret differences in their study time (Experiment 1) or in another learner's study time (Experiment 2) as reflecting either differences in data-driven regulation or differences in goal-driven regulation. This manipulation was found to moderate the relationship of both study time and rated effort to JOLs. The results were seen to support the idea that JOLs are based on study effort but the effects of experienced effort are mediated by an attribution that intervenes between the metacognitive regulation of effort and the monitoring of one's learning. The results invite an attributional theoretical framework that encompasses both data-driven and goal-driven regulation and incorporates the option of attributing experienced effort to either or both of the 2 types of regulation.