This study investigated the efficacy of an evidence-based intervention aimed at enhancing middle school students' understanding of achievement emotions and their regulation. We used the control-value theory of achievement emotions and ability conception from emotional intelligence as a theoretical framework. Participants were 62 students followed longitudinally from seventh to eighth grade, assigned to an experimental or a control condition. Pre- and post-test measures assessed knowledge on achievement emotions, strategies to regulate achievement emotions, native language-related achievement emotions, and grades. The intervention was embedded within the native language domain and included ten units. We focused on a range of ten positive and negative, activating and deactivating emotions, and associated emotion regulation strategies. Compared to the control group, students in the experimental group improved knowledge of emotional lexicon and emotion strategies; they decreased some negative native language-related emotions; and only boys increased native language-related grades. The findings supported the efficacy of the training and were discussed referring to relevant theoretical approaches.