This chapter reports on ongoing research that has focused on supporting pre-service and practicing mainstream subject-area teachers to develop disciplinary semiotic and pedagogic knowledge. It aims to provide a principled rationale for the design and application of curriculum literacy units for secondary teachers, with a focus on fostering a more equitable engagement of the EL's students and other linguistically and socio-economically diverse learners. The chapter presents recent developments in the understanding of semiotic knowledge in secondary content-areas and relevant pedagogic principles for its teaching and learning. Principles related to the why, the what, and the how of teaching and learning are discussed and exemplified through teaching cycles applied in the context of a curriculum literacy unit, integrating both knowledge about language and pedagogy and a range of critical perspectives that are key in contemporary reflexive pedagogies.