Financial market integration in Europe has evolved dramatically with the political, economic and monetary developments in the European Union (EU). In 2004, 10 countries from Central and Eastern Europe and the Mediterranean region joined the EU, which was the largest ever enlargement of the EU and a historic step towards unifying the whole of Europe after several decades of division that resulted from the Cold War. In this book, I want to focus on the financial integration, contagion effect and cause-effect relationship in the Eastern European. My results will provide lots of useful information for both policymakers and investors.