The objective of the study of the Irish Urban System and its Dynamics is to define and describe the system of cities and towns, including the economic and social functions of urban settlements of different sizes and to define the urban fields of cities and towns of population 5000+. For purposes of the study, urban centres are regarded as those with a population of 1500 or greater in 1996. The set of urban centres is illustrated on Fig. 1.1. Brady Shipman Martin undertook the study in association with NUI Maynooth and Fitzpatrick Associates. It involved the collation and analysis of a range of data on the size, functions and fields of urban centres, together with a review of previous studies of the urban system