Mountain pine beetle activity was monitored in one set of 2.5 acre plots in the southern portion of the Black Hills National Forest over a 17-year period. Beetles attacked 77 percent of the trees in the uncut control, 48 percent of the trees in the growing stock level (GSL) 100/110, 53 percent of the trees in the GSL 80/90, and 9 percent of the trees in the GSL 60/70. The percentages of MPB-attacked trees in each 1 in diameter class were lowest in the GSL 60/70, intermediate in the GSL 80/90 and GSL 100/110, and highest in the uncut control. Live basal area was significantly reduced in the GSL 80/90, GSL 100/110, and control but not in the GSL 60/70. Partial cutting to reduce beetle-caused mortality may be ineffective for partially cut parcels of <10 acres if the partially cut stands are surrounded by unmanaged susceptible stands. To increase the effectiveness of partial cutting, stands should be managed on a landscape basis. A 100-ft-wide strip with stand density of ?GSL 70 between unmanaged and managed stands may be sufficient to limit the spread of beetle-caused mortality from unmanaged stands to adjacent partially cut stands.