Tree species composition and structure was determined for an old bottomland hardwood forest located in the Moro Creek Bottoms Natural Area in south-central Arkansas. Diversity for this forest was high with species richness ranging from 33 for the overstory and sapling strata to 26 for the seedling stratum and Shannon-Weiner values of 2.54 to 1.02 for the overstory and seedling strata. Sweetgum (Liquidambar styraciflua L.) and oaks (Quercus spp.) dominated the overstory stratum with 66 percent of the importance values. American hornbeam (Carpinus caroliniana Walter) dominated the midstory and sapling strata with 32 and 42 percent of the importance values. Despite the large tree sizes and ages of several trees, comparison of the forest with models of bottomland hardwood succession and eastern United States old-growth definitions indicate the forest can best be described as old pioneer in transition to changing old growth.