This report reviews studies on language teachers as materials developers in language education, particularly focusing on how language teachers act as materials users, materials analysts, and materials designers when engaging with language learning and teaching materials. We contend that the three dimensions of materials development - that is, materials use, materials analysis, and materials design - intersect with one another, and that language teachers play a critical role in all three. Therefore, this review concludes with a research agenda that centres on language teachers as materials developers to expand our understanding of their roles in materials development.