The overlapping of the competencies of a number of regional authorities and those of the EU has necessitated an introduction of the regions in the EU policy-making. In this contribution, this phenomenon is combined with the concepts of paradiplomacy and multilevel governance. The present opportunities for regional participation will be looked at and some kind of classification scheme will be proposed. Those opportunities may be classified into four categories, depending on the formal (strict procedures) or informal (no strict procedures) and direct (direct relationship with EU institutions) or indirect (relationship with the EU via the central state) character of the participation. References are made to the Flemish involvement in European decision-making in the environmental field.