The book describes a quarterly macroeconometric multi-country model for Croatia, Bosnia and Herzegovina, Slovenia and Serbia. The model is tested by evaluating its ability to reproduce the endogenous variables in an ex post simulation. Furthermore, economic policy simulations are performed to analyse (i) islated vs. coordinated fiscal policies, (ii) the future of the euro area and impacts on Slovenia and Serbia, (iii) budgetary consolidation strategies for Slovenia, (iv) how to cope with population ageing, and (iv) impacts of Croatia's EU accession. Klaus Weyerstrass is senior researcher at the Institute for Advanced Studies, Vienna.