From the latter part of 1950s to 1977 in Sri Lanka, inward-looking economic development policies and import substitution industrialization strategy were given priority. There was increased government intervention and state regulation of economic activities in this period. Since 1977, the government has been deregulating, privatizing and opening up the economy to international competition. The main objective of this study is to examine the impact of outward-looking development strategy on the economy of Sri Lanka. The study exposes that under the outward-looking development policy, the country was able to acquire a great success and a noteworthy accomplishment in the growth of economy than inward-looking economic policy introduced in before 1977. Specially, Sri Lankan economy has been performing relatively well, with continuous increase in GDP per capita and an increase in exports of goods, and also it has managed to reduce poverty. The highest rate of unemployment in the country during the period 1950 to 1977 has been reduced under the open economic policy. Apart from that, a sharp development is remarkably observed in the fields of education, health services, nutrition, housing facilities and infrastructure facilities etc. Further, during the period 1950 to 1977, the annual growth of industrial sector was 3.4% has developed up to 7% after 1977.