This study used idiodynamic methodology to investigate the dynamics of second language (L2) learners' foreign language anxiety (FLA) and foreign language enjoyment (FLE), and the details of emotion regulation (ER) directed at managing these emotions, in pair- and group-work speaking tasks performed by 10 advanced English-as-a-foreign-language (EFL) learners. L2 classroom tasks were video recorded and then while viewing them, participants registered their emotion ratings per second. In stimulated-recall interviews, they revealed the causes of emotional intensity fluctuations and ER strategies used to manage the emotions. Additionally, the adapted Cognitive Emotion Regulation Questionnaire was used to collect quantitative data from a larger same-population sample (N = 103). The major high ecological validity results concerned (a) the highly individual patterns of emotional intensity fluctuations, with FLA fluctuating more than FLE, (b) the common triggers and mitigators of FLA and FLE--including specific errors, performance deficits, and message-conceptualization problems--and FLE triggers and mitigators related to its social aspect, (c) the varying degrees of the relationship between FLE and FLA, which depends on communication dynamics, and (d) a range of ER strategies, including their chains (sequences) and clusters (co-occurrence), with a special focus on the most common category--namely, cognitive ER, some types of which emerged as automatic ER processes.