This dissertation explores how financial market imperfections affect different aspects of the economy. The researchers use models to study the impact of financial integration on developing countries, the flow of capital between rich and poor countries, the role of incomplete information in saving behavior, and the effects of fiscal rules on government spending. They find that opening capital markets can harm capital owners in developing countries, financial imperfections can explain capital flows from poor to rich countries, incomplete information can significantly affect saving decisions, and debt-intensive fiscal rules can lead to better economic outcomes.