The problem is that the main control of the economy that the government uses is the level of the interest rate. Within any curency there can only be one interest rate. So the same interest rate would apply in England, Germany, Italy, etc etc. This causes a big problem in regional economies. At present in Britain, some areas have relatively high unemployment, whilst some have almost none, ideally the interest rate would be lowered in areas of high unemployment, but raised where there is near full employment (to stop inflation). Unfotunately, as we all use the pound, the interest rate must be the same, so some areas are left in economic depression. Within Britain, eveyone speaks the same language and it is easy to move around and get a job in another region, so the problem is not so serious. Within Europe under a single currency, this has not been as easy. The clearest example was in the first year or so of the Euro. Spain, Germany, France and Italy 's economies were floundering, especially Spain. All had relatively high unemployment, falling investment, hardly any growth ( near depression) and they needed the interest rates to be very, very low, in order to stimulate their poorly run economies. Ireland however, was near booming, and was suffering from the side effect - inflation. Ireland was in desperate need of higher interest rates, which of course were not forthcoming, the result was price inflation in Ireland. THis is very simplified but it shows how economies whose economic cycles are out of sync find it very hard to exist under the same interest rate - especially when EMU leaders had agreed that they wouldn't use short term tax rises and decreases to stimulate their economies in the place of interest rate controls. It would seem foolish to sacrifice control of the economy just for a few pounds saved on holiday money every year, especially as I don't go away to the EMU zone much anyway :)