歐盟多層次治理由超國家歐盟機構、國家、跨國家網絡與次國家代表團體串聯而成，此四層次行為者緊密相關並互動產出歐盟政策。此模式進而延伸至歐盟境外治理，使得管制(regulation)增加，區域無政府狀態也漸趨向制度化(institutionalized)。三大同步進展的推動力導致歐盟多層次治理。其一，歐盟公民共享世界觀形塑出歐盟內部一致性；其二，歐盟中央化(centralize)成員國不能或不願治理之議題領域；其三，歐盟分裂化(fragmentate)其治理權威予跨國家網絡與次國家代表團體。歐盟境外治理以其周邊為主，其面向潛在會員國的擴大政策(enlargement policy)將區域和平共榮區大幅擴張，為國際關係史上的巨大成就。同時，歐盟對於非潛在會員國的境外治理行為模式漸受關注。此即會籍條件性(membership conditionality)與政策條件性(policy conditionality)的比較。 　　歐盟地中海政策即歐盟對於非潛在會員國境外治理的個案。相較於以中東北非區域或非洲區域為整體，地中海區域主義更加密切，並因而有其研究價值。歐盟作為成員國集體行動的代理人(agent)，在歐盟地中海政策的推展中，也漸產生前述的多層次治理模式。本文對歐盟地中海政策網絡進行檢驗，並發現其與主權國家的外交政策的相異性。就低主權爭議性而言，跨國家與次國家層次有效迴避殖民遺緒爭議與干涉內政疑慮；就高政策滲透性而言，跨國與地方網絡易於串聯滲透至地中海區域公民社會、企業及地方代表機構之中，有助於促成文化同質性與共同生活經驗，並從根本上促進和平共榮區的目標；就低強制性而言，歐盟地中海政策中的共有制(co-ownership)精神，國家、跨國家與次國家層次的自願參與及水平式合作，都使得地中海夥伴國較以往更願意納入歐盟地中海政策的治理網絡之中。 / EU multilevel governance consists of supranational institutions, nation states, transnational advocacy networks and subnational representative bodies. The interplay of these four levels contributes to EU policies, and even EU external governance, which mainly focuses on its neighborhood. EU enlargement policy toward potential member states successfully expands EU area of peace and prosperity. Meanwhile, EU external governance in non-potential member states become systematic and obvious. EU Mediterranean policy is a case of EU external governance in non-potential member states. Compared to the development of regionalism in Middle East and North Africa (MENA) or Africa, regionalism across Mediterranean Sea is much stronger and thus worth more researches. EU promotes its Mediterranean policy in a way of multilevel governance as well, especially after Arab uprising in 2011 as EU starts to cooperate more with legislatures and non-governmental organizations in Mediterranean regions instead of depending on governments there. This thesis examines the networks of EU Mediterranean policy and figures out that they are different from diplomatic policies of sovereign states. First, they involve less sovereignty issues since transnational and subnational level effectively avoid post-colonial disputes and intervention concerns. Second, they are highly accessible because of their strong connections with civil society, enterprises and local representative bodies in the Mediterranean region. Third, they uphold principle of co-ownership and political pluralism and participants are thus more willing to join the policy networks.