ABSTRACT
This chapter reviews the relationship between theory and practice in specific domains of materials development: the four skills and vocabulary and grammar. The chapter begins with a discussion of how far materials development constitutes a field in its own right. It then covers each domain in turn, outlining theoretical principles advocated in the literature, the rationale for these principles, and the challenges they provide for materials designers aiming to produce theoretically informed materials. The principles adduced from the literature in each domain are then distilled into a smaller number of themes which emerge from a consideration of the principles.
