One of the main controversial issues in the field of teaching English as a foreign language in México is the decision to use students' mother tongue as a means and an aid for language teaching instruction. On these grounds, the purpose of this study was to explore undergraduate students' preferences and perspectives towards the use of their mother tongue as part of their teaching practice of English as a foreign language. Data obtained from the study favored the English-only language policy known as the monolingual approach. On the other hand, those students who exhibited preference towards the use of their native language reported that L1 is a useful learning tool used by instructors to establish class rapport, help convey meaning, and clarify task instructions. Results may provide useful insights to orient both language educators and language policymakers who are looking for answers on this regard.