Dolomite prairies are rare natural plant communities, with a few high-quality examples in northeastern Illinois. In this study, three dolomite prairies located in southwestern Will County, Illinois, were surveyed to assess species composition and quality. Two of the dolomite prairies were located on the Des Plaines Wildlife Conservation Area (i.e., Blodgett Road Dolomite Prairie Natural Area and Grant Creek Nature Preserve) and the third in the Midewin National Tallgrass Prairie (i.e., Exxon Mobil Natural Area). Overall, a total of 438 taxa were recorded: 318 at Blodgett Road, 255 at Exxon Mobil, and 270 at Grant Creek, with 129 common to them all. Of these, 97 were mesic or wet prairie species, 26 were nonnative taxa, and six were native woody species. Three state endangered and two state threatened species were found associated with these dolomite prairies. The Blodgett Road site was dominated by the annual grass Sporobolus vaginiflorus, along with Andropogon gerardii, Sporobolus heterolepis, and Ambrosia artemisiifolia. The Exxon Mobil site was dominated by the exotic species Poa compressa and Daucus carota, and several native taxa including Sporobolus vaginiflorus, Allium cernuum, Andropogon gerardii, and Solidago altissima. The Grant Creek location was dominated by Sporobolus heterolepis, Rosa carolina, Sorghastrum nutans, and Solidago altissima. These three dolomite prairies can be considered good quality natural areas based on species richness and floristic quality. However, the presence and occasional dominance of nonnative species suggests the need for implementation and continuation of management practices that should maintain or improve their quality.