Indian termination is a phrase describing United States policies relating to Native Americans from the mid-1940s to the mid-1960s. It was shaped by a series of laws and practices with the intent of assimilating Native Americans into mainstream American society. Cultural assimilation of Native Americans was not new; the belief that indigenous people should abandon their traditional lives and become what the government considers "civilized" had been the basis of policy for centuries. What was new, however, was the sense of urgency that, with or without consent, tribes must be terminated and begin to live "as Americans." To that end, Congress set about ending the special relationship between tribes and the federal government.

In practical terms, the policy ended the federal government's recognition of sovereignty of tribes, trusteeship over Indian reservations, and the exclusion of state law's applicability to Native persons. From the government's perspective, Native Americans were to become taxpaying citizens subject to state and federal taxes as well as laws from which they had previously been exempt.

From the Native standpoint, a former US Senator from Colorado Ben Nighthorse Campbell, of the Northern Cheyenne, said of assimilation and termination in a speech delivered in Montana:

If you can't change them, absorb them until they simply disappear into the mainstream culture.... In Washington's infinite wisdom, it was decided that tribes should no longer be tribes, never mind that they had been tribes for thousands of years.

The policy for termination of tribes collided with the Native American peoples' own desires to preserve Native identity. The termination policy was changed in the 1960s and rising activism resulted in the ensuing decades of restoration of tribal governments and increased Native American self-determination.