Addressing an underappreciated research area, this study reports on how two English language teachers in a Turkish tertiary education context use a global coursebook. At the beginning of the study, a metaphor elicitation task and pre-study interviews were employed to detect the teachers' coursebook conceptualizations. Then, a total of 12 lessons were video-recorded and adaptations were identified using a research-informed framework developed for this study. The participants examined and evaluated their own practices in stimulated recall sessions, reflective conversations and journal writing. The study was concluded with post-study interviews. Data revealed that the teachers' instructional practice was driven by the coursebook to a large extent as they stuck to minor adaptations and followed the guidance given by the coursebook. Along with the institutional constraints, the teachers' practices were influenced by their own personal preferences, attempts to make coursebook tasks accessible to learners, lack of planning and the highly structured delivery of tasks in the coursebook. However, pedagogic considerations were not foregrounded by the teachers. The results of the study call for professional teacher development on coursebook utilization, coursebook-based instead of coursebook-led program planning alongside redesign of coursebooks as resources rather than instructions.