We seek to measure the effects of fire and grazing on weeds of the northern mixed grass prairie. To accomplish this we are interpreting measurements from two management experiments, one at Lostwood National Wildlife Refuge (NWR) and one at Des Lacs NWR. At Lostwood we found a nearly balanced 2x7 treatment experiment with seven burning treatments (0-6 burns), two grazing treatments (+/-), and four habitat types (bottoms, n-slopes, s-slopes, and hilltops). The responses of nine weeds including Bromus inermis, Poa pratensis, and Symphoricarpos occidentalis have been recorded at five sites in each unit x environmental type (500 samples). The invasiveness of each plant was indexed with frequency measures and its tendency to dominate was indexed with cover measures. The data have been analyzed by multiple regression of 'presence' against habitat, number of burns, the Habitat by number of burn interaction, season of burn, years since burning, grazing (+/-), and number of grazing treatments. The study has been replicated at Des Lacs NWR. This experiment has eight burning treatments (0-7 burns), two grazing treatments (+/-), 4 habitat types (bottoms, n- or e-slopes, s- or w-slopes, and hilltops) and four reps. The same weeds were studied and with the same measures.