The paper discusses the strong output decline in the countries of Central and Eastern Europe. It starts from the puzzling observation that the former CSFR, Hungary and Poland experienced a relatively similar decline in output in spite of completely different stabilization and transformation policies. Using an aggregate supply/demand (AS/AD) framework it can be shown that there are obvious `real' causes for an output drop. The command economy was characterized by a dual disequilibrium (labour market and goods market). The removal of the high excess employment leads to an inevitable drop of natural output and employment together with a reduction of real wages. This is amplified by a downward shift of the production function, mainly because of lack of corporate governance. With very flexible nominal wages, the transitional economy can be represented by the `classical' version of the AS/AD model, which suggests that the theoretical basis for demand-side explanations is rather weak. This supply-side view is compatible with the popular explanation given by Calvo and Coricelli, but their evidence for a `credit crunch' in Poland is not very strong. The paper also discusses the `Soviet trade shock' as a possible cause for the output drop. It shows that Hungary and Poland -- and to some extent the CSFR -- were able to compensate their loss of CMEA exports by expanding their exports to the West, so that an overall trade shock cannot be observed. The `classical' explanation of the output decline rules out policies stimulating demand. What is required is a framework enhancing the transfer of resources from state-owned enterprises to the emerging private sector.