This study constitutes an interpretive case study to explore the preparatory year programme (PYP) of a newly established university in Saudi Arabia. The number of Saudi universities has drastically expanded from eight public universities by the end of the twentieth century to more than twenty-six public universities besides several private universities nowadays. This study investigates the relationship between language education policy (LEP), the perceptions of English as a foreign language (EFL) teachers towards using L1 in teaching L2 and these teachers' language practices inside the classroom with a focus on the role of L1 and the use of code-switching between L1 and L2. This study adopts an interpretive case study approach to analyse the EFL classrooms in this university. The LEP of the PYP towards L1 and the EFL teachers' perceptions towards using L1 are explored using audio-recordings of semi-structured interviews with the Director of the English language centre and four EFL teachers. Two of the participants speak English as their L1 and the remaining three participants speak Arabic as their L1 and English as their L2. The language practices of the EFL teachers are assessed through classroom observations and their reflections using an audio-recorder and fieldnotes. The audio recorded interviews, classroom observations and reflections are verbatim transcribed and analysed using NVivo. Data analysis reveals that L1 is banned by the LEP of the PYP, but the EFL teachers are not certain about this ban. The EFL teachers do not support or implement this ban on L1. The participants report that they do not always implement this policy by using L1 themselves and/or their students. My EFL classroom observations reveal that the EFL teachers do not always implement the LEP of the PYP towards L1 by using L1 themselves and/or permitting their students to use it in varying degrees. This use of L1 is not random, but it is used to serve particular functions of code-switching. These functions aim to achieve core goals or framework goals that assist in improving the classroom environment.