On a multifaceted basis, this paper explores the challenges experienced by native and non-native English language teachers (NESTs and NNESTs) in a tertiary-level EFL setting in Turkey. Adopting a qualitative case study design, the data were gathered from five NESTs through interviews and from five NNESTs through hand-written accounts based on the template for challenges in ELT (TCELT), and analysed through deductive thematic analysis. The findings showed that the NESTs and NNESTs perceive similar as well as different challenges in the language preparatory program where they are co-teaching. Student-related and institutional parameters accounted for the NNESTs' problems, whereas on the part of the NESTs, teacher-related and cross-cultural factors accompanied these parameters. The findings were furthered by the teachers' elaborations on the causes and pedagogical consequences of the challenges, and their strategies for coping with them. In light of the teachers' accounts, the paper concludes by offering several suggestions for the elimination of the perceived challenges in an attempt to improve the effectiveness of the program.