Cross-border regional development is one of the EU current major concerns. These regions are usually less dynamic socio-economically. Some of them have recently benefited from new roads, which have mainly been funded through the European financial program of Transnational Transport Networks, TEN-T. Using socioeconomic data from the Portugal/Spain cross-border area a model able to measure the relation between accessibility and development in this region is being calibrated. This paper reflects an initial study using Portuguese and Spanish geographical units in the border area for the period 1991-2001 and giving special efforts to the building of similar spatial units in both countries.