While focusing on the fifth enlargement, this study tries to analyze the main dynamics, important issues, dimensions and factors in the process; the most important effects, expected by the current members and candidates, from the enlargement process are also analyzed. For the current members, the enlargement meant access to a larger market, investment opportunities and employment. The Enlargement, as a painful and humiliating process wherein the burden of transformation left to the candidates, contained implied threats. Those who did not accomplish the compliance faced with the possibility of being labeled as 'non-Europe'. The theoretical and historical background of the enlargement, the dominant characteristics and historical and emotional factors are explained in brief. The supply and demand side of the enlargement and the negative effects of EU's not having a clear perspective about its objective are analyzed. In the fifth enlargement process the members were initially divided as drivers and brakemen. The mechanism of the enlargement was fairly strictly based on conditionality. The members also evaluated the possible repercussions of saying "no" to the enlargement.