Language users are creatures of habit with a tendency to re-use morphosyntactic material that they have produced or heard before. In other words, linguistic patterns and tokens, once used, persist in discourse. The present book is the first large-scale corpus analysis to explore the determinants of this persistence, drawing on regression analyses of a variety of functional, discourse-functional, cognitive, psycholinguistic, and external factors. The case studies investigated include the alternation between synthetic and analytic comparatives, between the s-genitive and the of-genitive, between gerundial and infinitival complementation, particle placement, and future marker choice in a number of corpora sampling different spoken registers and geographical varieties of English.