The book discusses various arguments for and against Critical Period Hypothesis for the acquisition of foreign language native-like pronunciation. The research described in the book encompassed adult learners of English and Polish, some of whom mastered the pronunciation in such a way that they managed to pass off as native speakers of the target language. Various factors were examined in order to show their contribution to the ultimate success of the learners such as a learning setting, a length in learning and a training in foreign language phonology/phonetics.