It seems clear that, whatever interest the size distributions of cities may have in themselves, greater interest attaches not to the static curve of sizes, but to the growth processes of towns which first generate and subsequently maintain or alter the curves. The various attempts to derive theoretical distributions have worked from sets of assumptions about these growth processes, but have not explored the extent to which their assumptions may be reasonable or may be met with in the real world. Such an examination seems long overdue, less for the light which it might throw on notions about rank-size curve, than in its own right as telling us something about the nature of urbanization. In this chapter we shall therefore look at data on the growth of towns in England and Wales in the nineteenth century to see to what extent empirical questions about the process of urbanization can be answered as well as to develop some more general ideas about urban growth.