This book investigates the content of the grammar syllabus typically employed in mainstream English Language Teaching. Using a mixed-methods approach, the author examines how the syllabuses used in coursebooks are actually constructed, how they evolved and how valid their contents are as a basis for teaching. The research reported consists of a broad exploration of primary sources in order to outline the evolution of ELT pedagogical grammar; ten interviews with key ELT authors and publishing professionals, which allows for the investigation of the decision-making processes underlying the choice of grammar content in ELT teaching materials; and finally, the presentation of case studies which examine three areas of grammar, analysing the evolution of their treatment in ELT materials (both historical and contemporary) and comparing their current treatment to data on real learner use. This book contributes to the literature on syllabus design and pedagogical grammar and builds on existing research into materials design. It will be of interest to researchers and professionals working in the fields of applied linguistics, pedagogical grammar, curriculum design and materials design.