Studies focusing on affective factors/emotions in learning are a mainstay in second language (L2) research. L2 teacher-focused research has also made advances in this domain and established the importance of affective factors for both learners and teachers. Despite the field's understanding of the emotional complexity of L2 teaching, much remains undiscovered. The aim of this qualitative research was to investigate L2 teachers' (N = 21) emotional experiences in the classroom. Specifically, by using a teacher diary we set out to document: (1) the emotions teachers reported in their place of work and during their interactions with learners, (2) the classroom activities teachers were engaged in when they experienced specific emotions, and (3) the regulatory practices they engaged in when dealing with both pleasant and unpleasant emotions. Our findings show that L2 teachers most frequently experienced pleasant emotions such as satisfaction, joy, and pride. In regard to unpleasant emotions, they primarily revealed frustration, irritability, and disappointment. Both types of emotions were mostly instigated by their learners and were related to L2 classroom activities in the areas of grammar, speaking, and reading. The teachers admitted to regulating both pleasant and unpleasant emotions. Finally, teachers revealed that they used down-regulation, reappraisal, deep breathing, and suppression as the most frequent emotion regulation strategies.