ABSTRACT
This chapter provides an overview of the status quo of the research on individual difference (ID) factors in second language acquisition (SLA). It opens with a clarification of the scope and significance of IDs in second language (L2) research, followed by a discussion of the theoretical perspectives of the roles of ID variables in influencing L2 learning processes, behaviors, and outcomes. The section on theories includes nine excerpts authored by prominent figures of major SLA theories who first summarized the major tenets of the theory in question and then commented on whether and in what way ID factors impact L2 learning according to the theory. The remaining sections center on ID research, where the authors discuss the importance of construct validation and the types of evidence that need to be collected to establish construct validity; summarize major research streams and designs; and identify current trends, new directions, and issues that need to be addressed in future research. The chapter ends with an introduction to the organization and features of the current volume and a description of the template for the ID-related chapters and the template for the methods-related chapters.
