This paper discusses the claims put forward by Barbara Fredrickson and her broaden-and-build theory of positive emotions that suggests that certain positive emotions, such as interest, joy, contentment and awe, have the capacity to broaden individuals' thought-action repertoires. Such positive emotions might facilitate the discovery of new knowledge, alliances and skills towards building people's enduring personal resources (Fredrickson, 2001; 2004). These propositions may have a direct impact on the language learning and acquisition process, emotions being at the heart of teaching (Hargreaves, 1998) and learning. This may be particularly true for acquiring a new language, which is a significant investment of personal resources and utilization of personal strengths. The paper also examines the interactionist position in second language acquisition, in particular, Lev Vygotsky's sociocultural theory of human mental processing and his concept of zone of proximal development (Lightbown & Spada, 1999). The paper further discusses the possibility of complementing our knowledge of second/foreign language learning theories with the insight the broaden-and-build theory provides to the educational field. Finally, the criticism levelled at the hyperbolized role of positive emotions on human flourishing on the part of Lazarus (2003a & b) is critically analysed along with the different perspective of emotions he holds.