In this book, leading researchers in morphology, syntax, language acquisition, psycholinguistics, and computational linguistics address central questions about the form and acquisition of analogy in grammar. What kinds of patterns do speakers select as the basis for analogical extension? What types of items are particularly susceptible or resistant to analogical pressures? At what levels do analogical processes operate and how do processes interact? What formal mechanisms are appropriate for modelling analogy? The novel synthesis of typological, theoretical, computational, and developmental paradigms in this volume brings us closer to answering these questions than ever before.