The past decade has seen a blossoming of emotion research in applied linguistics, which led to a deeper understanding of the crucial role both positive and negative emotions play in the context of foreign language (FL) learning. In this paper, we will outline a research agenda arising from the rich knowledge gained so far, which we hope inspires researchers to pursue future directions which we consider highly relevant for both researchers and practitioners alike. Firstly, we review the development of foreign language learner emotion research and identify research gaps. This will be followed by a discussion of four broad areas in which we perceive the pressing need for future research to advance our understanding of the role of emotions in foreign language learning. These include 1) the diversification of emotions studied, 2) a better understanding of emotion dynamics, 3) the need to diversify research contexts, and 4) bridging the research-practice gap. For each of these areas, we will outline tasks, taking into account the latest developments in theory and methodology, which we hope will advance our knowledge gained from this dynamic, thriving field of study.