Abstract Five Central New York northern hardwood stands were regenerated by clearcutting method, and followed through 20 yr of development. Observations from permanent remeasured plots indicate that a closed canopy formed and completely shaded the ground by 10-15 yr. Data gathered before that time did provide general information about features like the proportion of area stocked with trees and the stem density. After canopy closure, no new species entered the stand. Yet the actual species composition continued to change throughout the 20 yr period. Additional changes will occur as relatively short-lived species like striped maple, pin cherry, and aspen die. For other species, the change of importance will continue to depend on differences in their growth rates and tolerance to shading. Collectively, these dynamics will likely prolong the relatively rapid shifting of species composition for at least one-third to one-half of a century. Such findings suggest that the onset of canopy closure marks the earliest time to glean realistic information about the future species composition of emerging even-aged northern hardwood stands, and that considerable uncertainty remains about what species will eventually dominate the sites. North. J. Appl. For. 13(4):189-194.