Broad-sense heritabilities were 0.44 to 0.47 for height, 0.24 to 0.28 for diameter, 0.26 to 0.29 for volume, 0.69 to 0.70 for specific gravity, 0.36 for fiber length, and 0.83 to 0.89 for resistance toMelampsora rust in a breeding population of 100 eastern cottonwood clones from central Mississippi grown for 1 year on Commerce loam and Sharkey clay in 10×10 triple lattice designs.