This paper studies the fundamental determinants of cross-country differences in finnancial development. Two prominent tools for addressing model uncertainty, Bayesian Model Averaging and General-to-specific approaches, are jointly applied to investigate the financial development effects of a wide range of variables taken from various sources. The analysis suggests that the level of financial development in a country is determined by its institutional quality, macroeconomic policies, and geographic characteristics, as well as the level of income and cultural characteristics.