歐洲社會民主主義與共產主義皆源自馬克思的社會主義，俄羅斯無產階級革命成功後使得兩者在實際作為中開始分化。隨後社會民主主義在西歐議會制度中得以持續發展，而第二次世界大戰後東歐則被蘇聯納入共產主義陣營之中。然而，歷經近百年的實踐後兩者終究殊途同歸，其同歸的方式是由社會民主主義更新發展成為更符合現代政治價值的「第三條路」，尤其蘇東劇變後的20年間，東西歐的左派政治皆已趨於穩定，特別是東歐各國的共產黨繼承政黨在社會民主化後，更能相繼以聯合政府的方式取得上臺執政的機會。 其中最受國際關注的，便是摩爾多瓦共產黨於2001年2月2日在國會選舉中獲得眾多選民的支持，在國會101席中取得71席的絕對多數，令其有權單獨組成政府，更尤甚者，推舉出自家的共黨總統沃羅寧；2005年沃羅寧二度蟬連總統職位，並由摩共繼續組成政府。自2001年起至2009年已連續執政八年，從執政前摩爾多瓦的政治背景、摩共得以重新回朝的原因探究，到其執政後國內外政治的重要議題，皆是本文專章著墨的重點。 本文認為：第一，社會民主主義在後蘇20年中，積極從事理論與實踐的改革，在老左派與新右派之間已經走出新的「第三條路」；第二，研究摩共得以重新上臺的因素，除了本身對於政治制度的探索與改革之外，轉型時期的經濟危機與府會之爭，以及共產遺緒效應皆為主因；第三，摩共執政八年在經濟調息與外交政策的表現上成績斐然，但逐年下降的民主化評比卻突顯出共黨一貫僵化的政治思維，外加第二任期的經濟表現停滯，導致摩爾多瓦共產黨最終還是淪為最大在野黨。 / Both Social democracy and communism are derived from Karl Marx’s Socialism. However, they had come to a parting of the ways after the success of the proletarian revolution in Russia. Social democracy continued to develop under the parliamentary system in Western Europe, while communism thrived in Eastern European countries, which were controlled by USSR after WWII. Coming into the 21st century, however, the two reconciled and have once again merged and redefined themselves as “the Third Way”, which adapts itself to certain modern political values, and it had been growing steadily in the first two decades following the dissolution of Soviet Union. In Eastern Europe, successors of communist party have adapted themselves to this “Third Way”, which helped them come into power one after another by forming coalition governments. Among them, it was the Party of Communist of the Republic of Moldova (PCRM), which attracted international attention. The PCRM has won an absolute majority, gaining 71 out of a total of 101 seats, in the 2001 Moldovan Parliamentary election, enabled it to form the government, as well as, electing its very own communist President Vladimir Voronin. In 2005, the PCRM has once again won the election, and made President Vladimir Voronin re-elected to a consecutive term. The PCRM was in government between 2001 and 2009 for 8 years, and this research will look into a wide range of issues including the political background of PCRM, accounts of its regaining of political power, and important decisions of domestic and foreign policies made by the PCRM government. The first part of this research argues that social democracy had been actively reforming both in theory and practice in the two decades after the dissolution of USSR and it has successfully created a “Third Way” as opposed to the Old Left and the New Right. The second part argues that PCRM’s return to office can be attributed to its self-reformation, economic crisis, confrontations between the President and the Parliament in the period of transition, as well as, the communist legacy. In conclusion, it is argued that, although, PCRM government has made great achievements in foreign policies and in restructuring economy, Moldova’s score on democracy has worsened during its time in government, reflecting the ossified political ideology of communist party. It is this ossified political ideology alongside with the economic stagnation in its second term that led to the defeat of PCRM in the 2009 election and sent it back to opposition majority in the Parliament ultimately.