Emotion is "the primary human motive" (MacIntyre, 2002, p. 61). The human brain is an emotional brain, creating relationships among thought, emotion, and motivation in a complex dynamic system (Dörnyei, 2009). Emotion "functions as an amplifier, providing the intensity, urgency, and energy to propel our behavior" in "everything we do" (MacIntyre, 2002, p. 61). As a background to the author's own research with learner histories and as a means of deepening her understanding of learner anxiety and other emotions, she decided to study emotion theories. This article grew from that passionate interest. In this article, her aim is to describe several focused theories of emotion drawn from psychology and psychospirituality and to explain how they apply to L2 learning. The article is organized into the following theories: (a) resilience theory, (b) emotional intelligence theory, (c) well-being theory in positive psychology, (d) the theory of flow, (e) emotion theory in existential psychotherapy, and (f) psychospiritual concepts of emotion. Each of these theories has implications for L2 learners, who experience a very wide array of emotions as they attempt to develop language proficiency.