Tamástslikt Cultural Institute, Native American cultural museum in Pendleton, Oregon.

Tamástslikt Cultural Institute is a museum in Pendleton dedicated to presenting the history and culture of the Cayuse, Umatilla, and Walla Walla tribes. The institution displays artifacts, photographs, and interactive exhibits that document daily life, traditional practices, and the ongoing presence of these communities.

The Confederated Tribes of the Umatilla Indian Reservation proposed the institute during the 1993 Oregon Trail sesquicentennial, seeking to tell the trail's story from a Native American perspective. After federal funding was denied, the Oregon Legislature allocated at least $666,000 in lottery funds, and a $6.5 million Bureau of Indian Affairs loan guarantee followed in 1994. Ground was broken on June 9, 1995, and the institute opened to the public on July 31, 1998, with Roberta Conner as first director.

The name Tamástslikt comes from the Walla Walla North East Sahaptin dialect and was suggested by Átway Celia Bearchum; the verb tamásclik means "to turn over", as in the turning of seasons or years. Elders chose it over the longer original title for practicality.

Visitors can book guided tours and explore a gift shop with handmade items created by local tribal artisans. School groups can take part in educational programs designed to complement what they see in the galleries.

The museum is organized into three sections called We Were, We Are, and We Will Be that connect different time periods. This structure follows the tribal motto Cháwna mun na'ámta and reveals how past, present, and future are woven together.