American sycamore was grown at densities ranging from 200 to 27,000 trees per hectare. At 6 years of age, total height was greatest at stocking levels of about 1,000 to 5,000 trees per hectare; stem diameters were largest at low through intermediate densities. Proportion of branchwood per tree increased as stocking decreased. The most green weight yield, approximately 60,000 kg/ha, occurred at the highest density. Moderate competition among trees was necessary to obtain maximum height growth and a high ratio of stemwood to branchwood. Forest Sci. 24:493-496.