This thesis discuss the functioning of the EMU-project in connection to the crisis years from 2008 and up to the present date. This is essed in light of existing optimal currency area theory (OCA) and monetary policy theory. Whether EMU can be considered an optimal monetary union is large discussion. I try to shed some light upon this discussion using some specific approaches.The European monetary union was effective from 1999, with euro banknotes and coins not introduced before 2002. First, eleven countries joined (Belgium, Germany, Ireland, Spain, France, Italy, Luxembourg, the Netherlands, Austria, Portugal and Finland), and as of 2013 the EMU consists of seventeen countries (Greece 2001, Slovenia 2007, Cyprus and Malta 2008, Slovakia 2009 and Estonia 2011). In the first years few argued the EMU’s success. Growth was high in almost all member countries, and some countries in the periphery stood out with even higher growth than the core. Unfortunately the economic prosperity did not last forever.Today the situation in the EMU is quite different from what it was the first years after the creation. At present the EMU is experiencing high unemployment and slow growth. In March 2013 the overall unemployment rate was measured to be 12.1 % (Eurostat), and youth unemployment even reaching the double of this number in many countries. To which degree is some countries problems today related to their membership in the EMU? There exists a lot of theory on what needs to be present for a monetary union to work optimal. In this thesis I will present some of this theory, including some monetary theory, and then discuss the EMU-project with these aspects in mind. I will mostly use the Taylor rule as a point of departure for how the national economies would have liked to see monetary policy being conducted. Did the divergences between the members become too big? How ill-suited did the single ECB interest-rate become for some members? Would some countries have had advantages from being able to conduct a different policy both before and after the crisis in 2008? Have any countries been able to utilize their position outside the EMU? This is the kind of questions I try to address in this paper. For this purpose I draw on research papers, statistical databases (OECD and Eurostat) and my own analyzes. Alongside a general assessment of the differences within the EMU I approach these questions in two distinct ways. First, taking a closer look a country (Ireland) that might have had too different economic performance from the core of the EMU, and second, comparing a country within the union with a country outside (Netherlands and Sweden).The chapters 2-4 go through theory central for our later discussion. Chapter 2 consists of monetary theory I find relevant and the arguments for the inflation-target framework present in most developed economies today. Chapter 3 is an introduction to some of the key-concepts in OCA-theory. Chapter 4 looks into the role of the ECB, their tools and objectives, and describes the instruments they have at their disposal for conducting monetary policy. The last 3 chapters seek to explore some of the problematic aspects of the EMU project the last crisis years. In chapter 5 I try to address the differences in economic performance between the EMU-countries. Here I also look at the differences between what interest rate a Taylor-rule would predict for each country and what was set by the ECB, and address differences in inflation rates and output-gaps within the EMU. I use the Taylor-rule as a proxy for how a hypothetical national central bank would have liked to see monetary policy being conducted. Chapter 6 takes a closer look at Ireland as the deviant in the EMU, with economic activity diverging excessively from the core, and try to address whether they could have utilized from having a national central bank. Chapter 7 is an attempt to assess whether it could have been advantageous to stay outside the currency union through the last year’s economic distress. To do this I compare Netherlands and Sweden. Netherlands as member of the currency union and exposed to the monetary policy the ECB decides upon, and Sweden with a national central bank with the possibility to conduct independent monetary policy. In this chapter I try to assess whether different economic performance can be related to their different policy regimes, namely, whether Sweden’s role outside the EMU is the source of different economic performance from the Netherlands.