This dissertation investigates the history of derived nominalizations in English from 1500 to the present day, with special reference to the deverbal nominalizing suffix -(t)ion and the deadjectival nominalizing suffixes, -ness and -ity. The data are drawn from two historical corpora of English texts: The Early Modern section of HCET (Helsinki Corpus of English Texts, 1500-1700), and ARCHER (A Representative Corpus of Historical English Registers, 1650-1990). The case studies are situated within an integrated theoretical framework of change in derivational morphology which addresses neologising, productivity, variation, lexicalization and semantic change. Morphological productivity, a topic typically treated in synchronic morphology, is placed at the centre of this framework. The rationale for this approach is that the measurement of productivity provides a way to observe change in progress in derivational morphology. The chief task then, is to develop procedures for measuring productivity in historical corpora. The history of the suffixes will be investigated quantitatively by measuring their productivity across temporal periods and across text-type/register, and qualitatively by analysing derived nominalizations in discourse contexts to understand the effect of register and/or text type on nominalization. The result is a socio-historical account of derived nominalization, which demonstrates the ways in which neologising (and thus productivity) can be driven by contextual factors, discourse processes and stylistic considerations.