In Ireland, policy on literacy now aims to expand the role that post-primary teachers of all subjects have in developing students' literacy skills. This paper draws on data from a wider research study carried out in secondary schools in 2010 and focuses on the classroom support with disciplinary literacy provided by subject teachers for students who have literacy difficulties. A brief outline is provided of the context and perspectives informing the study as well as the research methods used. Findings are examined against the backdrop of policy developments for literacy at second level and within the context of wider policy change. Teachers' lack of professional knowledge, combined with barriers at wider system level, is identified as a significant challenge to pedagogical change at classroom level. Implications for policy implementation, for initial teacher education and for cultural change at school level are discussed. It is argued that literacy must be repositioned as a central aspect of subject pedagogy and teachers, as subject experts, supported in unpacking and sharing with students, the discourse practices and ways of viewing and communicating about the world that are characteristic of their academic disciplines.