["European Journal of Education, Volume 61, Issue 3, September 2026. ", "\nABSTRACT\nForeign Language Enjoyment has received increasing attention in second language acquisition due to its role in fostering engagement and communication. Although previous research has often treated enjoyment as a relatively stable trait, perspectives informed by Complex Dynamic Systems Theory (CDST) suggest that emotions are dynamic, non‐ergodic, and fluctuate over time. Drawing on CDST, the present study adopts an idiographic approach to investigate second‐by‐second changes in foreign language enjoyment during conversational tasks. Six young language learners participated in recorded interactions on four different conversational topics, followed by idiodynamic self‐ratings and stimulated recall interviews to explain emotional fluctuations. The findings revealed nonlinear, individualized trajectories of enjoyment, highlighting substantial within‐person variability. Fluctuations were closely linked to topic familiarity and interest, idea availability, perceived task difficulty, and cognitive effort. Familiar and meaningful topics generally facilitated higher enjoyment, whereas unfamiliar or cognitively demanding topics led to declines; however, moderate challenge occasionally enhanced engagement. This study highlights the dynamic and context‐sensitive nature of foreign language enjoyment. These results also underscore the importance of examining emotional experiences at a micro‐temporal level and demonstrate the value of the idiodynamic method in capturing fine‐grained affective dynamics during language use. The study contributes to a more nuanced understanding of how contextual (e.g., conversational topics) and cognitive‐linguistic factors shape learners' emotional experiences during real‐time communication.\n"]