In order to fulfil the requirements for the degree of Doctor of Philosophy in Economics and Finance, at the University of St.Gallen, after the completion of the course-work and research phases, I hereby to provide the cumulative dissertation. The dissertation consists of three essays on macroeconomic policy, development economics and economic growth. The first chapter examines empirically the relationship between the cyclical pattern of fiscal policy in democratic developing countries and their quality of political institutions. This chapter uses updated data to analyse 63 developing countries from 1980 to 2013 and robustly shows that pro-cyclical fiscal policy exist in both democratic and non-democratic developing countries. The main contributions of this chapter are controlling the endogeneity issue by using the instrumental variable method and investigating the interactions between political institutions variables and the cyclicality of fiscal policy. The results suggest that an improvement in the level of institutional quality plays an important role to restrain pro-cyclical fiscal policy. These effects are larger in democratic countries than non-democratic ones. Additionally, the maturity and stability of a democratic regime influence in restraining the implementation of pro-cyclical fiscal policy. The second chapter studies the effects of demographic transition and unfunded pension system in affecting the economic growth of Thailand. The chapter adds the aspect of the informal sector and investments in children's education into the Overlapping Generation (OLG) model. We modify the model to allow individuals heterogeneity in their ages and exogenously assign to work either in the formal or informal sector. The results from our model suggest that the non-contribution pension system or old-age security schemes hinder the economic growth of the economy with a high share of the informal sector and low fertility rate like Tha.