This exploratory sequential mixed methods study (Creswell, 2015) sheds light on the role of first language (L1) in the second language (L2) classroom. The study, conducted in four public schools in Jordan where Arabic is the L1 of both teachers and students, and English is taught as a foreign language, explored Jordanian English as a Foreign Language (EFL) teachers' (N=7) attitudes toward using Arabic (L1) to teach English (L2) and the perceived functions and/or negative ramifications of such use. It additionally investigated 104 Grades 10 and 11 students' beliefs regarding their teachers' use of L1 in the L2 classroom. Data was collected through two rounds of interviews (pre-observation and post-observation), questionnaires, and seven class-observations. The study found that EFL teachers were highly aware of the importance of minimizing the amount of L1 use, which was influenced by the type of lesson and the proficiency level of students. The study suggests that teachers used L1 to achieve six different functions in the L2 classroom which they believed could enhance L2 teaching and learning, (i.e., translation, metalinguistic use, overcoming some teaching challenges, giving instructions, motivation, and avoiding some words in L2 that sound taboo in L1), but they also believed that L1 overuse may limit L2 development, and it may also have negative affective ramifications. The students' beliefs regarding their teachers' reasons for using the L1 in the classroom were in line with the teachers'. The findings of this study paint a clear picture of the L2 teaching reality in foreign contexts and suggest that policy makers should consider changing L2 teaching policies which do not, at present, welcome any role for L1 in the L2 classroom.ii