A system dynamics model reflecting the structure of the interaction between the .two languages operating in the Basque Country has been built. People have been classified into three different groups depending on their knowledge of the language. These groups of population are subjected to a normal demographic evolution and to a linguistic interaction. The interaction among the populations is controlled by two major levels: the basque culture and the development factors of the language. The only exogenous input to the model are political actions to raise or to decrease the development factors level. Although the model proves to be sensitive to these actions a delay time of about sixty years is to be expected in the response of the population.