In the last three decades, brightly colored images of neural activity in the media have enhanced interest in brain functions. As a result, people have become more aware of the fact that cognition is not simply a black box. Instead, it consists of dynamic systems and mechanisms that respond to stimuli and which educators can exert influence on. In this paper the author shows how three areas of neuroscience are of crucial importance for L2 instruction. First a brief overview of studies is provided which show that words are not just encoded as labels for concepts, but rather are stored in brain networks together with the perceptions and actions that are relevant to them. From this point of departure the author goes on to demonstrate that sensorimotor encoding is the natural way to learn L2 vocabulary. Secondly, the concept of mirror neurons is introduced. They represent the neurobiological basis for imitation and are therefore essential for learning, particularly for the acquisition of languages. Thirdly, the author deals with brain maturation and elucidates its effects on L2-learning proficiency at different ages. These three lines of evidence suggest that knowledge of brain mechanisms is crucial for language teachers. Briefly stated, the aim of this paper is to help to bridge the gap between language instruction and neuroscience.