Knowledge of both the vegetation and soil seed bank of a community is necessary to understand species storage and regeneration potential. Species composition and abundance were assessed in Thomson-Fulton Sand Prairie in northwestern Illinois, U.S.A. Species richness, evenness and floristic quality were greater for the vegetation than the seed bank. Jaccard's index of similarity was 36. In total, 43% of vegetation species were represented in the seed bank and 67% of seed bank species occurred in the vegetation. Native perennial grass and forb species dominated species richness and % cover of the vegetation. In the seed bank, native species also exceeded introduced species, but annual species exceeded perennial species in species richness at the plot level. The relatively low correspondence between above- and below-ground community structure indicates that, in this grassland, seed banks function as storage for only a sub-set of species and many species in the vegetation must rely on sources other than the seed bank for regeneration.