Age has often been considered a major, if not the primary, factor determining success in learning a second or foreign language. Children are generally considered capable of acquiring a new language rapidly and with little effort, whereas adults are believed to be doomed to failure. Although older learners are indeed less likely than young children to master an L2, a close examination of studies relating age to language acquisition reveals that age differences reflect differences in the situation of learning rather than in capacity to learn. They do not demonstrate any constraint on the possibility that adults can become highly proficient, even nativelike, speakers of L2s. Researchers, in other words, have often committed the same blunders as members of the general public: misinterpretation of the facts relating to speed of acquisition, misattribution of age differences in language abilities to neurobiological factors, and, most notably, a misemphasis on poor adult learners and an underemphasis on adults who master L2s to nativelike levels. By clarifying these misconceptions, we hope this article will lead to a better understanding of L2 learning and, in turn, better approaches to L2 teaching.