ABSTRACT
A great number of individual difference factors have been examined to account for considerable variations in L2 grammar attainment. In the first part of this chapter, the roles of two major factors—age of onset and cognitive aptitudes—that received focal attention in predictive research of L2 grammar learning are reviewed. L2 grammar acquisition in both naturalistic and classroom settings is viewed from the perspectives of L2 theories of explicit and implicit learning. The second part of this review focuses on how learners’ individual difference factors, particularly cognitive aptitudes, moderate the effectiveness of different types of L2 grammar learning conditions in instructed settings. In particular, aptitude-treatment interaction patterns are summarized for extant research on oral and written corrective feedback types and the timing of grammar instruction and practice. Future directions of research that strike the balance between theoretical integrity and pedagogical relevance are presented to further advance our understanding of individual difference factors in L2 grammar learning.
