This study examines the effects of EU accession on local policies and institutions in Southeast Europe, focusing on the EU's enlargement strategy following the 2004 expansion. It compares the integration processes of regional countries such as Greece, Bulgaria, Romania, Croatia, and Turkey, evaluating Turkey's candidacy within the framework of accession negotiations that began in October 2005. The study analyses the transformations undergone by these countries' political, legal, and economic systems during the process of aligning with EU standards.