Self-regulated learning (SRL) refers to students being responsible for their learning. It involves goal setting as well as regulation of cognition, emotions (affect), motivation, and behavior (e.g., through management of the learning environment). A critical component of SRL is metacognition, whose function is to monitor and control cognitive processing. Metacognition has three facets, namely metacognitive experiences, metacognitive knowledge, and metacognitive control. Each of them contributes in different ways to the regulation of learning. Specifically, metacognitive experiences and metacognitive knowledge serve the monitoring of cognition and provide information necessary for control decisions such as allocation of study time or strategy use. Metacognitive control comprises metacognitive strategies (or skills) such as orientation, planning, checking, and evaluation. It is worth noting, however, that there are interactions between metacognition and affect, so that metacognitive control decisions are based not only on task demands and features of cognitive processing but also on students’ affective experiences and motivation during task processing. Interventions using metacognitive constructs show how metacognition can be applied in the classroom to increase the efficiency of learning. However, it is possible to develop alternative interventions that take advantage of the interactions between metacognition and affect. This gives new directions in the way SRL is promoted in the classroom. Research on metacognition and SRL provides a rich theoretical ground upon which to build classroom interventions. Meta-analytic evidence suggests that SRL can be cultivated in educational contexts already from preschool and primary education. Most of interventions aimed at fostering metacognitive knowledge, strategies, and skills in school settings resulted in significant overall effects on academic performance. The magnitude, though, of the effect sizes in these interventions is moderated by various student, training, and context-related factors. A new direction in the way SRL is promoted in the classroom is to develop interventions that take advantage of the interactions between metacognition and affect. Specifically, applying metacognitive skills on learning-related subjective experiences and emotions to increase self-awareness can facilitate learning. Given that students substantially benefit from direct instruction of SRL skills, future studies should focus on training teachers how to teach them.