Metacognitive monitoring skills are crucial for middle school students to improve academic performance and promote self-regulation. The current study examined the effect of social interaction on metacognitive monitoring training assessed by calibration accuracy measures and performance on comprehension items. Sixth-grade students (N = 84) assigned to competitive, cooperative, and individual conditions completed multiple-choice comprehension items and item-level confidence judgments for expository and narrative reading passages in eight sessions distributed over six weeks. Results indicated no improvement in monitoring accuracy due to classroom conditions. In contrast, overconfidence increased for students in the competitive condition across the intervention. However, students in the cooperative condition demonstrated higher comprehension on the final training passage relative to students in the other two conditions. In addition, text interest was positively related to students' judgment accuracy in the cooperative and individual conditions but not in the competitive condition. This study underscores the importance of social context with regard to metacognitive processes and performance outcomes during classroom instruction.