Assam considered as the gateway to the Northeast of India was a hot bed for numerous socio-political crises in the last two decades of the 20^th centuries. It is a land of rich natural resources such as oil, tropical forest, tea, coal, timber, silk etc. The strong sense of exploitation and deprivation has helped to generate the separatist tendencies among the masses of the region. It is said that Assamese nationalism articulated first in 1979 as a protest against immigration from Bangladesh. A moderate section of leaders of the Assam movement demanded detection and deportation of all foreigners from Assam. On the other hand the radicals formed the militant organization i.e. ULFA (United Liberation Front of Assam). During this period some youths decided to take arms to carry out armed struggle to bring a revolutionary change in the political sphere of the state. Corruption in the government machinery, unemployment, influx of illegal migrants, exploitation of natural resources by the Central government without any benefit of the local people contribute the youths to support ULFA. During its first five years of it establishment this militant organization had not only engaged in some unlawful activities but also on some constructive works. But gradually, they lost its popularity and strength due to numerous factors. In this work an attempt has been made to analyze the activities of ULFA which had a great impact on socio-political and economic scenario of Assam in the last decade of the 20^th century