Four Pinus contorta X banksiana hybrids developed in California were planted on two sites in Montana and one site in Idaho to determine whether they were suited to climate and soils of these three test locations and whether they were superior to Montana lodgepole pine. Height, diameter, crown width, number of branches per whorl, vigor, and survival were measured 5 and 10 years following establishment. Hybrids were well adapted to climate and soils. Most hybrids did not exceed height growth of Montana trees except in Idaho, where Montana trees are not indigenous. A limited test using Montana and Idaho genotypes for the seed parent showed these genotypes to be superior to California genotypes for developing hybrids for these areas.