Economic literature has shown the important and prominent role of financial development in economic development and growth, through the effective pooling and allocation of national savings towards investments in support of economic development. Hence, it is highly important to look for the real determinants of financial development. This study investigates the determinants of the financial development of Syria, Lebanon and Jordan for the period between 1995 and 2014, by applying the method of Ordinary Least Squares (OLS), to a set of determinants adopted in previous studies. The study found a statistically significant effect of only three of the nine determinants tested on the level of private credit by depository institutions (financial sector activity). It also concludes a statistically significant effect of only five determinants on the level of Liquid Liabilities (financial sector size). The determinants are: inflation, bank concentration, rule of law, control of corruption, contract enforcement and improving supervision of banks. Reforms that contribute in reducing corruption, enforcing contracts, improving the rule of law, improving supervision on banks, reducing the level of inflation and the level of bank concentration, are the most important factors that we need to focus on in the long run, to achieve financial development (size and activity).This in turn contributes to real economic development in Syria, Lebanon and Jordan.