This chapter examines the constraints and pedagogical considerations involved in implementing Genre-Based Instruction (GBI) within English for Specific Purposes (ESP) courses in EFL contexts. It synthesises insights from major genre traditions while focusing on how limited genre exposure, prescriptive grammar instruction, and responsive task orientations shape learners’ engagement with genre. The chapter argues that while GBI provides powerful tools for supporting academic and professional writing, its effectiveness depends on the broader ecosystem in which it is embedded—particularly teacher expertise, curricular alignment, and instructional time. Drawing on empirical studies, it highlights the challenges posed by fluid genre boundaries, variable learner preparedness, and constrained instructional conditions. These factors can limit the development of transferable genre competence, especially for novice writers. The chapter concludes by pointing to the need for complementary pedagogical frameworks.