Education systems around the world have moved to develop literacy progressions that describe a sequence of development in oral language (talking and listening), reading/viewing and writing. In Australia, the National Literacy Learning Progression (ACARA, 2021) is designed to support students' literacy development across the years of primary and secondary school. Common arguments for the use of such descriptions include the need to provide extra detail to official English syllabuses, and to inform teachers' pedagogical choices of the next logical focus for teaching. However, while it is understandable that teachers want to identify their students' needs and to plan for their development, there is slim evidence for common and systematic progression through stages of literacy development for all students. In this paper we report on a review of the literature into literacy development (Weekes, forthcoming) pointing out the gaps and discontinuities in the existing research as well as demonstrating the highly contextualised nature of literacy growth. We argue such factors pose significant challenges for policy and curriculum writers charged with responsibility for producing literacy progressions.