The basis of this research is the compilation of a gazetteer of sites and finds of the La Tène and early Gallo-Roman periods (c. 475 BC - c. 31 BC) in north-west France. Two aspects of the evidence thus collected are examined in detail: settlement and coinage. For the early La Tène period, burial evidence provides the only significant source of information, and at present it is not of sufficient quality or quantity to do more than shed light on a few specific aspects of regional development. Similarly, the settlement evidence from the later periods is also relatively scarce. However the introduction of coinage in the middle La Tène, probably via mercenaries returning from service in the Greek world, provides a much more substantial body of information on developments between the third and first centuries BC. Following a consideration of the theoretical aspects of coin use and function, all the major types of coinage in north-west France are examined in detail, and a number of problems of attribution and interpretation are discussed. It is apparent from the study of settlement and coinage that several traditional interpretations of aspects of the La Tène and early Gallo-Roman periods in north-west France need to be reassessed, in particular questions concerning the development of oppida, and the function of coinage. In the concluding chapter a model of the development of coinage in the region is suggested, illuminated where possible by the application of settlement evidence. The result demonstrates clearly the extraordinarily cohesive nature of this area, which has been termed "greater Armorica", throughout the later Iron Age and into the Gallo-Roman era.