This article reports on the qualitative findings of a mixed methods study that investigated primary school teachers' beliefs, practices and choices of resources for teaching written grammar. Qualitative data were collected from Primary teachers in Western Australia through semi-structured interviews (n = 10) and analysed thematically. Although all participating teachers reported that they saw the teaching of written grammar as important, it was found that they had insecure Pedagogical Content Knowledge about Grammar (PCKAG). This insecure knowledge base coincided with eclecticism in pedagogical practice and the choice and use of resources that were not optimal for building PCKAG, or for supporting best practices in the instruction of written grammar.