The Assam Agitation (or Assam Movement) was a popular movement against undocumented migrants in Assam between 1979 and 1985. It is regarded as one of the most vibrant democratic mass movements of independent India. The movement, led by All Assam Students Union and the 'All Assam Gana Sangram Parishad', set an agitational program to compel the government to identify and expel the illegal immigrants. The agitational programs were largely non-violent, but there were incidents of acute violence, like the Nellie massacre. The agitational program ended in 1985 following the Assam Accord that was signed between the agitation leaders and the Government of India.
The agitation leaders formed a political party, Asom Gana Parishad, which came to power in the state of Assam in the Assembly elections of 1985 and later in 1996.
In 1978 the member of the Lok Sabha, Hiralal Patwari, died necessitating a by-election in the Mangaldoi Lok Sabha Constituency. During the process of the election it was noticed that the electorate had grown phenomenally. AASU demanded that the elections be postponed till the names of foreign nationals are deleted from the electoral rolls, and the Assam Agitation was born.