In the last few decades regulation -political, of capital accumulation- has been extended in a set of scales (global, state, regional/county, local), that do not act in a hierarchic way, but simultaneously and in an equalitarian mode. It has favoured the relationship between collective actors and institutions of the different scales across the borders, giving place to the emergence of a new scale, the lateral one, which is apparent in the phenomena of transnational, interregional, and cross-border cooperation or conflict. In the article I approach diverse topics of this last scale. I study the aims and policies of the European Union concerning cross-border cooperation, the meaning of the ideal type of Euroregion, as well as the intersection of the remaining scales with cross-border cooperation. I analyze the context, or structure, of cross-border cooperation, which in the European Union is specified in the emergence of different Axes (Lotharingian or Central, Mediterranean, Atlantic). I finally examine the problems faced by the undeniable transnational and transfrontier dynamics of labour relations in the European Union.