The purpose of this chapter is to examine the influence that external actors have on regional development. Having considered the impact that the European Union is having on regional relations in the Mediterranean, a review of the influence that the leading actor in international relations, the United States, and the most powerful political and military alliance in the vicinity, NATO, are having on regional rela­ tions in the Mediterranean follows. A specific effort will be made to investigate the reasons behind extra-regional powers involvement in the internal development of international regions. This will include exploring the extent to which external actors can influence the basic pattern of regional alignments.