In this article I put forth the core argument that Second Language Acquisition (SLA) needs to account for the psychological and emotional dimensions of second language (L2) learning, but that a number of epistemological and methodological difficulties must be surmounted before this new research program can be a reality. To illustrate my arguments, I examine in depth 2 research programs developed by my colleagues and me over the last decade: research on extraversion as a psychological variable investigated within the tradition of individual differences in SLA, and research on the expression of emotion in the L2. Throughout the article, I argue against research isolationism and for more interdisciplinarity in the field of instructed SLA. I contend that research on instructed SLA would benefit from an increased methodological and epistemological diversity and that a focus on affect and emotion among researchers might inspire authors of teaching materials and foreign language teachers to pay increased attention to the communication of emotion and the development of sociocultural competence in a L2.