Expansion of an eastern hemlock (Tsuga canadensis) forest was studied in a north-facing ravine system in the eastern piedmont of Maryland. Based on size-class distributions, historical photographs, distribution of standing live and fallen decaying trees, and diameter growth rate regressions, the forest appears to be a climax community expanding throughout the ravine system, including deciduous upland areas between ravines. Coverage increased from 6.1 ha to 29.7 ha between 1938 and 1986 and is expected to reach at least 119 ha in the absence of fire, logging, overbrowsing by deer, and catastrophic wind.