Mountain pine beetle infestation was detected in stands on the east side of Glacier National Park and the adjacent Blackfeet Indian Reservation in 1979. Infestation in the Park now encompasses an estimated 215,882 acres. About 200 acres are infested on the reservation. In areas sampled, number of trees killed per acre increased from 2.3 trees in 1977 to 18.9 in 1979. Predicted mortality, plus management alternatives to prevent or reduce infestation severity, is discussed.