Located on the ninth floor of the old main Post Office, the Bureau of Indian Affairs (BIA) office was occupied several times by Native activists who were advocating for more resources and more of a voice within the BIA in the late 1960s and early 1970s.

The sit-in on December 26, 1969 was organized by the Native American Committee, a group formed within the American Indian Center to support Red Power activism. The committee occupied the BIA office to support the occupation of Alcatraz Island (1969-1971) by the group Indians of All Tribes and other Native activists. By December, the Alcatraz occupation had entered its second month of what would become a two-year occupation.

Another one of the most publicized sit-ins by Native activists in Chicago occurred on Monday March 23, 1970. This was part of a coordinated mass sit-in campaign that also included five other BIA offices in Denver, Colorado, Santa Fe, New Mexico, Sacramento, California, Cleveland, Ohio, and Minneapolis, Minnesota. Leaders of the American Indian Movement (AIM) and other Native institutions argued that the BIA needed to assist Natives that lived off of reservations. The protests also critiqued the BIA more broadly, especially policies like the voluntary relocation program and Termination.

This sit-in at the Chicago BIA office resulted in 23 arrests on trespassing charges including Minnie Bacon, Mike Chosa, and Steven Fastwolf. However, like other national-level protests, these sit-ins also brought national attention to issues Native communities faced in cities and on reservations. Native activists sought aid to help with housing, health, job, and food security, which they had been promised through treaties and through the voluntary relocation program. These sit-ins were Native communities' way of exerting their right to aid.