This book provides an alternative to the "grammar debate" in second language acquisition theory and teaching. Accepting that language acquisition is at least partially input dependent, the author asks how grammatical form is processed in the input by second language learners and is it possible to assist this in ways that help the learner to create richer grammatical intake. He answers these questions and explains why traditional paradigms are not psycholinguistically motivated. Drawing on research from both first and second language acquisition, he outlines a model for input processing in second language acquisition that helps to account for how learners construct grammatical systems. He then uses this model to motivate "processing instruction," a type of grammar instruction in which learners are engaged in making form-meaning connections during particular input activities.