The problem of immigration is becoming serious day by day in Assam. It has deep impact on the socio-economic and political life of Assam. However, immigration is not a recent phenomenon in the context of Assam. It was the British government who, for the first time initiated the trend of immigration as a state policy into Assam. At the very outset, immigration was primarily concerned to economic activities, but later it was more political rather economic. Besides, immigration in the beginning was very small. It was not viewed as a threat to the Assam’s society. But in the subsequent days, the pace of immigration reached into such a stage which posed great challenges to society of Assam. Therefore, in this writing an attempt is being made to understand the histogenesis and the impact of immigration on the society of Assam.