The thesis is divided into three chapters.

1) I study how monetary policy should be optimally designed when households show financial wealth heterogeneity.
Main results: thanks to its ability to affect interest payments volatility, monetary policy has real effects even in a flexible-price cashless-limit environment; second, in a setup with nominal rigidities, price stability is no longer optimal. The extent of deviation from price stability depends on the initial level of debt dispersion.

2) I assess the role of housing price movements in influencing the optimal design of monetary policy.
Under the optimal simple rule, housing price movements should not be a separate target variable in addition to inflation. Furthermore, the welfare loss arising from targeting housing prices becomes quantitatively more significant the higher the degree of access to the credit market.

3) I analyze the effects of fiscal policy in a currency area.
Results: a public spending shock in one region increases private agents demand for imports and appreciates the terms of trade; second, a countercyclical fiscal rule can restore the Taylor principle, the uniqueness of the equilibrium and reduce macro-volatility.