This explanatory mixed-methods study investigated the use of bilingual students' linguistic repertoire for teaching and clarifying grammar. A repeated-measures design was used in which the quantitative data were complemented with follow-up qualitative data. Data were collected in six treatment sessions and from twenty-five all-male twelfth-grade state-school students from Bandar Turkman, Golestan, Iran. A three-phase experiment was carried out involving teaching six grammar lessons to one group: (1) in English only; (2) in the students' local language; and (3) their official language, which was followed by a semi-structured interview. The results of the quantitative data analysis indicated that translanguaging through incorporating students' linguistic assets proved to be an effective strategy which allowed students to have a deeper understanding of grammar. The analysis of the qualitative data showed that language learners had a positive attitude towards this pedagogy and believed that it promoted their language learning, motivation and self-confidence. Implications of the study for language teachers and researchers are discussed.