Introduction

This chapter provides a brief overview of the history of research methods used in studying child second language (L2) learners, from the seminal work on L2 morpheme acquisition by Kenji Hakuta (1974, 1976) and Dulay and Burt (1974) to recent focuses on L2 child learners’ unique aspects and contexts of learning. As the introductory chapter in this book, this chapter defines the target L2 learners as children who learn additional language(s) between the ages of 4 and 12, and clarifies the main concepts that are relevant to the entire book, such as simultaneous bilingualism and sequential bilingualism. Brief summaries of individual chapters are also included. The chapter concludes with a discussion of this book’s aim and intended readership.