Despite widespread consensus among educators that "active learning" leads to better outcomes than comparatively passive forms of instruction, it is often unclear why these benefits arise. In this article, we review research showing that the opportunity to control the information experienced while learning leads to improved memory relative to situations where control is absent. By integrating findings from a wide range of experimental paradigms, we identify a set of distinct mechanisms that mediate these effects, including the formation of distinctive sensorimotor associations, elaborative encoding due to goal-directed exploration, improved co-ordination of selective attention and encoding, adaptive selection of material based on existing memory, and metacognitive monitoring. Examining these mechanisms provides new insights into the effects of active learning, including how different forms of active control lead to improved outcomes relative to more traditional, passive instruction.