This study investigates the effects of metacognitive intervention in first language on the listening performance of young-adult English as foreign language (EFL) learners in Iran, and probes the learners' attitude toward such intervention in English as foreign language classrooms. The participants in the study were 61 young-adult EFL learners divided randomly into two groups: An experimental and a control group. Following Metacognitive Pedagogical Sequence and its importance in listening comprehension, the participants in the experimental group underwent an eight-week intervention delivered in L1 including the linear instruction of metacognitive strategies assisting their metacognitive awareness of the processes in second language listening. The control group, however, followed the conventional pedagogy of the language institute. The data were collected in the learners' listening performance before, and after the intervention through listening comprehension test. The analysis of the quantitative data shows that metacognitive intervention in first language leads to a significant improvement in the overall listening performance of the learners. Similarly, the results of the interviews show that the Metacognitive Pedagogical Sequence and the presentation of metacognitive strategies in first language lead to learners' higher listening performance and better mastery of note-taking and word-meaning guessing.