The transition of the Eastern Central European countries from centrally planned economies to developed market economies has been one of the major structural changes in Europe. It started a new stage of enlargement of the European Union. The monograph presents the results of an international research effort aimed at the analysis of macroeconomic aspects of joining the European Union by the Central European countries. This analysis was based on country and world economy models and rests on a series of alternative scenarios of economic development up to the year 2010. It provides the reader with a broad historical background and a discussion of recent trends of Central Europe. It summarises the experience of the new members of the European Union. The scenario simulations show the likely path of future economic development for the Czech Republic, Poland and Slovakia, analysing the pros and contras of joining the European Union.