In this groundbreaking monograph, Anna Maria Di Sciullo proposes that asymmetry -- the irreversibility of a pair of elements in an ordered set -- is a hard-wired property of morphological relations. Her argument that asymmetry is central in derivational morphology, would, if true, make morphological objects regular objects of grammar just as syntactic and phonological objects are. This contrasts with the traditional assumption that morphology is irregular and thus not subject to the basic hard-wired regularities of form and interpretation.Di Sciullo argues that the asymmetric property of morphological relations is part of the language faculty. She proposes a theory of grammar, Asymmetry Theory, according to which generic operations have specific instantiations in parallel derivations of the computational space. She posits that morphological and syntactic relations share a property, asymmetry, but diverge with respect to other properties of their primitives, operations, and interface representations. Di Sciullo offers empirical support for her theory with examples from a variety of languages, including English, Modern Greek, African, Romance, Turkish, and Slavic.