ABSTRACT
Numerous studies have adopted a wide range of research designs, methodologies, and techniques to investigate the second language development of mood and modality. Regardless of the theoretical paradigm adopted or the research methodology used, what remains consistent in this body of research is the finding that the acquisition of mood and modality is a source of persistent difficulty for many second language learners, even at the most advanced stages of proficiency. The current chapter provides a discussion of these findings by focusing on how this research has contributed to theories of second language development, particularly within the generative paradigm, and the different methodologies that have been used. Although this chapter looks predominately at second language learners, we also discuss studies on first language and heritage speakers and comment on how these populations can inform our understanding of second language development. The chapter concludes with a discussion of future directions for research on the development of mood and modality.
