This book uniquely illustrates how second language acquisition (SLA) data can instigate linguistic exploration and help inform linguistic and acquisition theory in crucial ways. It also offers new perspectives toward our understanding of the relationship between first and second language acquisition, Universal Grammar (UG), and the target language input. Specifically, examination of the L2 development of pied-piping and preposition stranding in English questions and relative clauses shows that the required preposition is frequently omitted by learners who have demonstrated accurate...