This thesis is grounded in the discipline of marketing and draws, substantively, on literature from within the regarded sub-discipline of relationship marketing. However, the literature drawn upon is firmly interdisciplinary, drawing heavily on theories from economic geography. The crucial construct drawn from this outwith literature is that of geographic co- location, the phenomenon of geographic proximity between businesses and other organisations. This thesis isolates and defines two modes of regional marketing activity, a defensive and an offensive variant. It is to the defensive variant that this thesis makes contributions by proposing a macro theory of relevant marketing geography, a regional relationship lifecycle that examines the notion of loyalty to a region and a competence-based view of regional relationship marketing activity between co-located actors. The conclusions and models presented here mark the first thesis in the discipline of marketing examining the contribution of the marketing discipline to regional competitiveness. The thesis also deploys a novel methodology within the marketing discipline to understand the research phenomena in time and space, and in terms of agency and structure. The methodology developed for, and deployed in, this thesis is based on Anthony Giddens' theory of structuration