First published in 1983. The problem of defining a frontier region is a leitmotiv of this collection of articles but each perspective requires its own definition. The definition of regions has long been controversial and the attempt to define a sub-set of them - frontier regions - according to precise geographical or socio-economic criteria can be useful only for limited purposes as, for example, in the study of transfrontier labour markets. This text looks at the borders regions in Western Europe, in terms of transfrontier co-operation, geographical definitions, physical planning, economics and political authority.