Teachers' ability to accurately judge students' monitoring skills is important as it enables teachers to help students becoming better self-regulated learners. Yet, there is hardly any research on this crucial teacher skill and a framework is missing. We present a novel conceptual and methodological framework integrating teachers' judgments of students' monitoring skills with teachers' judgments of students' performance and students' judgments of their own performance. Using this framework, we explored teachers' ability to judge students' monitoring skills and students' performance. Secondary education teachers judged their own students' performance and monitoring on a reading comprehension test (N[subscript teachers] = 46; N[subscript students] = 406). Teachers' judgments of students' judgment accuracy deviated 14.33% from the actual accuracy of students' own monitoring judgments, with a tendency to underestimate their students' monitoring accuracy. Teachers' judgments of students' performance deviated 21.96% from students' actual performance, with a tendency to overestimate students' performance. So-called performance cues--pieces of information pertaining to students' prior knowledge and skills relevant to the performance task--appeared predictive or diagnostic both for students' performance and for students' monitoring judgments. When making accurate judgments, teachers used diagnostic cues to a greater extent than when making inaccurate judgments. Yet, when making accurate judgments, teachers also used two non-diagnostic cues (students' IQ and self-concept regarding reading comprehension). To further improve teachers' ability to accurately judge students' monitoring, it may be worthwhile to help teachers ignore non-diagnostic cues.