Extensive research has been conducted to understand how accurately students monitor their studying and performance via metacognitive judgments. Moreover, the bases of students' metacognitive judgments are of interest. While previous results are quite consistent regarding the importance of performance for the accuracy of metacognitive judgments, results regarding motivational and personality variables are rather heterogeneous. This paper reports on two studies that simultaneously examined the predictive power of several performance, motivational, and personality variables on metacognitive judgments. The studies investigated a set of judgments (local and global postdictions in Study 1 and global pre- and postdictions in Study 2) and accuracy scores (bias, sensitivity, and specificity) in two different settings. Individual differences in judgments and judgment accuracy were studied via hierarchical regression analyses. Study 1 with N = 245 undergraduate students identified performance and domain-specific self-concept as relevant predictors for judgments after test taking. This was consistently found for local and global judgments. Study 2 with N = 138 undergraduate students hence focused on domain-specific self-concept and extended results to predictions. Study 2 replicated results for global postdictions but not predictions. Specifically, before task processing, students' judgments relied mostly on domain-specific self-concept but not on test performance itself. The studies indicate that different judgments and measures of judgment accuracy are needed to obtain comprehensive insights into individual differences in metacognitive monitoring.