The soils of the prairie and adjacent forests of western Washington display features related to the two different vegetational assemblages. Climatic changes during the early part of the Holocene were responsible for the establishment of the prairie within a coniferous biome. The Spanaway soils (prairie) were further affected by infusion of charcoal from burnings induced by Indians. Spanaway should be considered, to an extent, an anthropogenic soil. Total C (14.4 percent), extractable C (8.0 percent), and N (1.10 percent) are all higher in the Spanaway than in the Everett (forest), but C/N ratio is wider in the Everett. Pedogenic Fe is higher in amount and more mobile in the Everett than in the Spanaway. Amorphous Fe reaches a peak in the B horizons of the Everett (Al, 0.49 percent; B2, 1.28 percent) but not in the Spanaway (Al, 0.53 percent; B2, 0.62 percent). Aluminum is preferentially complexed by the organic material of the Spanaway (Al2O322 percent, Al) more than in the Everett (Al2O30.90 percent, Al); pH and clay mineralogy are not apparently afiected by the differences in vegetation.