In this chapter, the units linked by the co-ordinator and are shown to correlate with orality: oral genres use more super-phrasal (e.g. clausal) co-ordination, while higher proportions of phrasal co-ordination characterize literate genres. A development towards more super-phrasal co-ordinationcan thus indicate colloquialization. Analyses demonstrate that newspapers, parliamentary debates, and letters written by men exhibit this very trend in diachrony, while women’s letters unexpectedly develop in the opposite direction. The latter change, however, is shown to be a result not of anti-colloquialization, but of an increased reliance on the sentence as a unit of written discourse in letters by women; main clauses are increasingly placed in separate sentences or separated by semicolons rather than being linked with dashes and co-ordinators, which was a feature of several women’s idiolects in the early nineteenth century. Sentence-initial and, which was a proscribed feature, is the focus of a separate study and is shown to increase in frequency in speech-based and speech-purposed writing. Overall, the results point to colloquialization in several genres.