Efklides and colleagues developed the Metacognitive and Affective model of Self-Regulated Learning (MASRL) to provide a comprehensive theoretical framework of self-regulated learning (SRL). The distinguishing feature of MASRL is that it stresses metacognitive experiences and other subjective experiences (e.g., motivational, affective) as critical components of SRL. The insights underlying the model are that metacognitive experiences are related to affect, and that metacognition, motivation, and affect interact in SRL rather than function independently. Moreover, the MASRL proposes that SRL takes place at two levels, the Person and the Task X Person levels, with the latter being specific to the learning task and its demands. Although SRL can start with goal setting and planning in a top-down manner, monitoring and control processes at the Task X Person level provide input for bottom-up SRL. To highlight the theory-building process that led to the MASRL theory, we present questions that inspired its conception, its theoretical underpinnings, and current evidence supporting it. We also discuss the implications of the MASRL theory for understanding SRL in the classroom and for teacher-student interactions. Finally, we discuss open questions and issues that future research on MASRL would address in the context of educational psychology and SRL promotion.