Few borders exist which separate two countries as dramatically disparate as the Dominican Republic and Haiti. Both share the territory of the Hispaniola island, but a profound process of differentiation rooted in the colonial division of the island between France and Spain and ideologically maintained by both modern nations, has lead to what Théodat (1998, 2003) calls the "twofold insularity" – each country behaves as if it were located on a separate island. In spite of all prejudices and ethnical, historical, linguistic, social, economic or religious differences, people living in the border regions established cross-border relations which, even if largely based on economic interests, are much more frequent and important to both nations than officially admitted (De Jesus Cerdano and Dilla, 2005; Sillé & Segura & Cabral, 2002). The local dynamic created by this exchange becomes palpable when one observes the busy binational market in the border towns of Ouanaminthe (Haiti) and Dajabón (Dominican Republic). Twice a week, people from nearly the whole northern part of both countries travel to these towns located on either side of the Masacre River, in order to buy and sell goods or to offer services in the market of Dajabón. The other days, tons of cargo transit to Haiti, to the extent that the once small borderland settlements have become an important junction in the economic subsystem of the northern part of the island. Moreover, the construction of a free zone in Ouanaminthe in 2002 –to produce textiles for the US-market– has connected the borderland towns to the international economy. This recent development is set within a context of progressive opening of borders (Martinez, 1994). It is the result of international policies that have been decided in the capitals, without consulting the concerned regions. In Ouanaminthe and Dajabón, local institutions are weak and receive no or little financial and administrative support from central administration. They do not have the means to cope with growing pressure on land and infrastructure, as the emergence of legal and illegal livelihood opportunities in the borderland has generated a threefold increase of the overall population in the past twenty years (Dajabón grew from 8'500 inhabitants in 1980 to 16'000 in 2002 and Ouanaminthe from 7'000 in 1981 to 39'000 in 2003). How did these recent economic, political and societal transformations shape the urban space of the two borderland towns? I addressed this issue by analyzing the motivation of stakeholders involved in the process of spatial transformation, and the impact of their actions. In my work I refer to the conceptual framework of urban intermediation (Bolay and Rabinovich, 2004), i.e. the spatial issues that each town has to address according to its internal characteristics, its function in national and international networks and its relation to the direct rural environment. In order to use this framework for the borderland issues, the conceptual part of this study proposes to develop the concept of "borderland intermediation". To the existing urban intermediation concept, it adds the influence of the characteristics of the border (based on policy and political aspects, economic issues, local identities, social networks, national defense issues and geographical insertion). By doing so, it relates the bi-national system of borderland towns to the intermediation concept. Data has been collected over three and a half years during several periods of fieldwork: observation and mapping of occupation and use of urban space, cartography, qualitative interviews with local stakeholders and residents, completed by other primary and secondary sources. This study shows that the recent transformations have accentuated the existing unbalanced relationship between the two towns. The powerlessness of the municipality of Ouanaminthe to meet population growth and to impose regulations or taxes related to the growing trade has enhanced its dependency to the Dominican town. For a growing number of Haitians, it is of existential importance to cross over to Dajabón in order to seek income, healthcare and education and this, in spite of latent racism and mistreatments. Founded on a strong sentiment of exploitation, Haitians often criticize the capitalist or even colonialist relationship imposed by their neighbors: not only the fact that the bi-national market takes place in Dajabón, but also that Dominican enterprises develop subsidiaries in Ouanaminthe, taking advantage of cheap labor and the absence of local production. On the contrary, the majority of Dajabón residents interviewed do not need to cross the river for their living. Most of them have never been to Ouanaminthe, but consider it insalubrious, out of control and dangerous. Both towns lack application of regulations in urban planning matters. Thus, spatial growth has entirely been ruled by landowner structure and land occupation practices. Around Dajabón, the adjacent land belongs mainly to two landowners, whose strategy –to enhance soil value through development of equipped middleclass neighborhoods– has restricted the urban sprawl. In Ouanaminthe land belongs to a multitude of small peasants. The selling and illegal occupation of rather small plots leads to sprawling urban growth, guided by rural pathways and leaving entire parts of neighborhoods inaccessible to motor vehicles. Population growth has also been absorbed by high densification of existing neighborhoods. No formal collaborations exist between the two municipalities. Informal ones do, through the implication of the two mayors, but overall, cross-border collaboration is left to NGOs and professional associations who militate for human rights, environmental issues and fair treatment inside the bi-national market. International development agencies present in the borderland initiate projects with bi-national concern, but these are disconnected from the local level and strongly influenced by the fact that these agencies relate directly to the central governments. We also observe a process of internal segregation in both towns, as commercial establishments progressively occupy parts of the town centers and the emergent middle class gathers in specific neighborhoods. Ouanaminthe and Dajabón are functionally interlinked and their transformation is undeniably governed by the progressive permeability of the border. Nevertheless, this border separates two completely different urban landscapes that are deeply marked by the internal characteristics of each town. Furthermore, the unequal and complex relationship of both populations creates the paradox that their spatial proximity accentuates the segregation in both towns, as it allows the citizens of both countries to stay in their environment and to commute –if necessary– even daily. This work shows that the application of the intermediation concept is relevant for the study of complex relationships that govern borderland space. The analysis based on this concept has enabled to study, on a local level, processes that are taking place on a global level. In so doing, it has allowed us to provide some answers to the central question: "How do local populations, national and international firms and governments react when a territorial economy, based on agriculture, is progressively linked to international networks? "