Izmir, the third biggest city of Turkey, holds an enriched culture shaped by consecutive immigrations of different ethnic, religious and cultural groups throughout the centuries. Up until the dissolution of the Ottoman State it was a multifaceted urban center of different religious, ethnic, and social communities, where the Muslim Turks were outnumbered by other communities. Izmir had also been a safe haven for the people migrating from the insecure parts of the Balkans of declining Ottoman Empire. In the foundation years of Turkish Republic, demographic picture of Izmir had substantially changed, other than two minor non-Muslim groups (Levantines and the Jews), the majority of the non-Muslims fled from Izmir, and it has, in a very short time, become a city of ethnic Turks. During this demographic shift two immigrant groups (Cretans and Thessalonicans) from the Balkans have emerged as prominent groups in shaping the identity of Turkish Izmir. Immigration from Crete began after the independence of Crete from the Ottoman Empire in 1898. Among the Muslim population in Izmir, Cretan Turks already existed as one of the large and important communities. The Exchange of Populations Agreement between Greece and Turkey in 1923 led to another wave of immigration, this time from Thessalonica to Izmir. After the deportation of the Greeks at the end of the Turkish Independence War, Izmir had been peopled by immigrants mainly from Thessalonica, and also from Crete (the last portion of Cretan Muslims), and from other Greek islands and the Balkans. Since then the Cretan and Thessalonican originated groups have been influential in social life of Izmir and its contemporary identity. This paper is based on a pioneering sociological study to find out the actual number of them, to map out their cultural traits and social views, and to pursue their contribution to the identity of Izmir. The results show certain distinguishing characteristics of the groups in which certain similarities and dissimilarities have been displayed. This study was executed and finished in 2008.