In this volume, Ray Jackendoff and Jenny Audring embark on a major reconceptualization of linguistic theory as seen through the lens of morphology. Their approach, Relational Morphology, extends the Parallel Architecture developed by Jackendoff in Foundations of Language (2002), Simpler Syntax (2005), and Meaning and the Lexicon (2010). The framework integrates morphology into the overall architecture of language, enabling it to interact insightfully with phonology, syntax, semantics, and above all, the lexicon. The first part of the book situates morphology in the language faculty, and introduces a novel formalism that unifies the treatment of all morphological patterns, inflectional or derivational, systematic or marginal. Central to the theory is the lexicon, which both incorporates the rules of grammar and explicitly encodes relationships among words and among grammatical patterns. Part II puts the theory to the test, applying it to a wide range of familiar and less familiar morphological phenomena. Part III connects Relational Morphology with issues of language processing and language acquisition, and shows how its formal tools can be extended to a variety of linguistic and nonlinguistic phenomena outside morphology. The value of Relational Morphology thus lies not only in the fact that it can account for a range of morphological phenomena, but also in how it integrates linguistic theory, psycholinguistics, and human cognition.