There are few studies of animal communities in coastal zones, especially those of herpetofauna. We conducted herpetofaunal surveys in open shoreline habitats for 3 yr in three large protected areas in the Mixedwoods Plains Ecozone of the southern Laurentian Great Lakes. These locations are isolated preserves in one of the most heavily human-modified areas of North America. We found 17 species with low to moderate similarity of species membership and highly uneven relative abundance and biomass. Common Five-Lined Skinks dominated communities in relative abundance, dominated biomass at one location, and codominated biomass with Common Gartersnakes and Eastern Foxsnakes or Milksnakes at the other two locations. Five other species also regularly inhabited the coastal zone, whereas others were more transient users. Review of species' dietary requirements suggest that consumption of arthropods and other invertebrates may play an important role in structuring the community. Both the legacy of historical and more recent anthropogenic changes have altered the structure of these communities into “novel ecosystems.” Further study of coastal herpetofaunas and their functional role in ecosystems is warranted.