This study is set out to explore teachers’ language use and language attitude towards the use of their mother tongue while teaching English to secondary school students. It has been discussed in various studies that teachers’ use of bilingual teaching method is helpful for learners to understand difficult concepts, vocabulary, grammar, and even for boosting learner’s self-confidence. Teachers’ perceptions of when L1 should or should not be used in L2 classrooms were also of interest in the present study. Semi-structured interviews were conducted with twenty-eight higher secondary school teachers. The consent of teachers was obtained before conducting the study. Participants’ responses in Bengali were transcribed, translated into English, and analyzed to arrive at the codes, categories, and themes. Kuckartz’s (2014) “thematic qualitative text analysis” and the six phases of thematic analysis (Braun and Clarke, 2006: 87) were followed. Participants reported that they use their mother tongue which is majority of the students’ L1 as a support language and English mostly during teaching. The findings showed that teachers had a positive attitude towards the use of L1 for the facilitation of L2 learning. Teachers believe that the use of L1 acts as a facilitating tool and helps learners to become proficient users. Teachers stated that the use of L1 aids low-proficient learners to get better exposure to English. The study presents serious considerations for policymakers, administrators, teachers, and learners about the importance of accommodating students’ first language (L1) alongside the English-only curriculum.