This dissertation deals with the issue of economic growth, specifically with the examination of the determinants of economic growth, from both a theoretical and empirical perspective. The first chapter introduces the issue and summarizes the main results. The dissertation is divided into three parts. The first part comprises of two chapters (chapters 2 and 3) considering the issue of per capita income convergence. The first chapter presents the theoretical background and re-examines the convergence debate among the neoclassical and endogenous growth models while the second chapter examines empirically the convergence hypothesis using both cross-sectional and time series econometric techniques for the case of Greek regions. The second part comprises of three chapters examining the unexplained factors affecting economic grwoth. The two first chapters (chapters 4 and 5) of this part deal with the neglected role of finance and financial intermediation in the process of economic growth of a country. One chapter presents the theoretical literature on this subject. Most of the empirical studies on the determinants of economic growth use cross-country analysis. Such an analysis, however, ignores dynamic information that can explain part of the variation in growth rates. In our empirical analysis, which is conducted in the fifth chapter, we employ time series techniques for the examination of the relationship among financial development and economic growth, using UK data. The third chapter of the second part (chapter 6) examines empirically the role of education, for the case of the greek economy. Finally, the last part examined the role of uncertainty on economic growth. Specifically, chapter 7 deals with the role of uncertainty steming from political instability on UK's economic growth using time series data and techniques while chapter 8, considers the role of uncertainty on investments and economic growth examining empirically its effects for a panel of 59 developed and developing countries.