Are the dimensions of morphological diversity dependent on the cognitive pathways for processing, storage, and learning of word structure, and if so, how? Conversely, are languages that differ in their morphological structure processed and learned in different ways? This volume examines the relationship between linguistic cognition and the morphological diversity found in the world’s languages. As the idea that domain-general cognitive processes and morphological typology are inextricably linked has moved into the mainstream of linguistics, the field has diversified conceptually and methodologically. This introduction to the volume offers an overview of conceptual issues that underpin the volume’s papers and some of the methodological trends they reflect. It thus serves as a roadmap for the papers that follow.