This document summarizes a research study on undocumented migration and public opinion in Greece. The study interviewed 778 people in Athens and Nafplion about their attitudes toward undocumented immigrants in Greece. It provides background on Greece's economic struggles following the 2008 financial crisis and the resulting 22% decline in GDP. High unemployment and economic failures have led Greek society to take extreme measures against undocumented immigrants. The document reviews literature on the relatively new concept of "illegal immigration" and how migration patterns have changed over time. Greece has shifted from being a country of emigration to one of immigration. The influx of immigrants, both documented and undocumented, impacts economies and can increase social tensions.