This paper discusses the challenges and possibilities attendant upon successfully implementing literacy across the curriculum initiatives--or "school language policies" as they have come to be known--particularly at the secondary or high school level. It provides a theoretical background to these issues, exploring previous academic discussions of school language policies, and highlights key areas of concern as well as opportunity with respect to school implementation of such policies. As such, it provides a necessary conceptual background to the subsequent papers in this special issue, which focus upon the Secondary Schools' Literacy Initiative (SSLI)--a New Zealand funded programme that aims to establish cross-curricular language and literacy policies in secondary schools.