This introduction aims to situate this monograph as a result of the work of the Topic Study Group (TSG) 38 at the 13th International Congress on Mathematical Education, held in Hamburg in July 2016. Beyond this goal, it aims to evidence the fact that, far from being an isolated work, the contributions received to this TSG, their number as well as their content, witness the emergence, at an international level, of a new field of research, dedicated to the teachers’ resources. After having set this scene, this introduction shortly overviews the chapters of this monograph, structured in four sections.