In many regions of the world, exotic or overabundant large herbivores are a concern for the conservation of forest plant communities. Previous work suggests that the impacts of white-tailed deer overabundance in North American forests are broadly negative. However, no quantitative synthesis currently exists to verify the generality or magnitude of these impacts. Using meta-analytical techniques, we show that white-tailed deer have strongly negative impacts on the diversity and abundance of forest understory plant communities, but these impacts are not ubiquitous for all components of the plant community. White-tailed deer have their largest impacts on woody plant species.