I propose a unitary framework to interpret the links between differences in financial structures
and the monetary policy regimes on the one hand, and the correlation of business cycles on the
other. Using a two-country micro-founded model with financial frictions I predict that a greater
financial diversity should reduce cyclical correlation under a given monetary regime, and that
moving from independent monetary policies to a hard peg or a common currency should increase
it, for any given degree of financial diversity. I use the recent experience of EMU to test these
ideas, and show that my model explains reasonably well the broad patterns of business cycle
correlation observed recently among the main euro area countries.