Building students’ literacy skills is a key educative purpose of contemporary schooling. While libraries can play a key role in fostering literacy and related reading engagement in schools, more needs to be known about school librarians’ role in promoting these goals. To this end, this article seeks to identify the nature and scope of the literacy supportive role required of the school librarian in the United Kingdom. It also investigates how this aspect is situated within the broader competing role requirements of the profession. Using a hybrid approach to content analysis including both qualitative and quantitative methods, this article presents in-depth analysis of 40 recent job description documents recruiting school librarians in the United Kingdom to investigate these research aims. The vast majority of documents (92.5%) included literacy supportive roles or characteristics of a school librarian, and recurring salient components included supporting literature selection, having a broad and current knowledge of literature, promoting and modelling reading for pleasure, devising and supporting reading and literature events, promoting a whole-school reading culture, working closely with students to support reading and literacy skill development, and implementing and supporting reading programmes. This literacy supportive role was found to sit within a potentially highly complex and diverse work role which may compete with the literacy supportive role for time and resourcing in school libraries. This research suggests that the role of school librarians in the United Kingdom is both complex and evolving, and that school librarians in the United Kingdom have a valuable literacy supportive role to play in their school libraries.