Abstract: The ecological functions provided by mature forested wetlands are continually being lost through permitted impacts associated with residential, commercial and agricultural development. In response, regulatory agencies require that forested wetlands be restored, established, enhanced or preserved (i.e., wetland mitigation) to replace those ecological functions. Assessments of wetland mitigation projects often focus on plant community characteristics as indicators of ecological integrity. Using the Vegetation Index of Biotic Integrity (VIBI) sampling protocol, we collected herbaceous and woody plant community data as well as physical habitat attribute data at four forested mitigation areas and four relatively undisturbed reference forested wetlands within the Erie/Ontario Drift and Lake Plains and Eastern Corn Belt Plains ecoregions of Ohio. The objectives of the study were to compare the plant community composition and structure of these areas and to identify factors that may be influencing their development. Our analyses revealed both compositional and structural differences between mitigation and reference areas and indicated that certain physical habitat features (e.g., hummocks, macrotopographic depressions and coarse woody debris) may influence plant community development. Past land use, disturbance history and landscape setting also likely played an important role in shaping the plant communities of the sampled areas. Mitigation areas supported fewer ecologically conservative species than reference areas and lacked a subcanopy of native, shade-tolerant wetland tree and shrub species. VIBI results indicated that reference areas were characterized by the presence of seedless vascular plants, a high Floristic Quality Assessment Index score, the importance of native, shade-tolerant species as well as high percent cover of sensitive species, hydrophytes and bryophytes. Mitigation areas were characterized by ecologically tolerant species, the importance of canopy tree species, and many trees in small diameter classes. These results suggest that forested mitigation wetlands may support plant communities dominated by species with a wide range of ecological tolerance and may lack the structure that characterizes mature forested wetlands. Assuming mitigation areas are on a desirable trajectory, several decades may pass before areas currently used for forested wetland mitigation begin to resemble relatively undisturbed areas in terms of plant community composition and structure. As more and more forested wetlands are negatively impacted by residential, commercial and agricultural development, there will likely be a continual decline in the functions provided by mature forested wetlands throughout Ohio.