The Eurozone is a monetary union; therefore, although the Euro fluctuates freely against other currencies, the exchange rate between the countries within the union is fixed. Why do some countries choose to join a monetary union? Obviously, there are strong arguments for adopting a common currency as well as strong arguments against giving up the national currency. Over time there have been numerous attempts of determining whether adopting a single currency is the best solution or not, taking into account the benefits as well as the costs involved by a monetary union. This paper will analyze the possible advantages and disadvantages of joining a monetary union, with an emphasis on the Eurozone.