This chapter provides a brief introduction to the broad underlying premise of this volume, namely, all learning activities require learners to be problem solvers. This is not problem solving in the typical subject-matter sense, such as in maths, solve for y: y + 6 = 10. Rather, while interacting with teachers, or studying alone, learners need to make decisions, that is – they need to solve problems – about selecting, applying, and monitoring useful motivational, cognitive, and metacognitive strategies to self-regulate their learning activities. Sometimes these problem-solving decisions are automated, tacit, and not very powerful, such as mindlessly selecting repetition as the best way to learn a vocabulary list. At other times, problem-solving decisions are effortful and creative, such as mindfully deciding to draw a concept map to elucidate the links between key ideas. Problem solving for learning matters because the quality of learners’ motivational, cognitive, and metacognitive decisions about how to approach a learning task affect the quality of their learning outcomes.