Long-term acidification of forest soils from atmospheric deposition of nitrogen (N) and sulfur (S) has been shown to deplete soil exchangeable base cations, increase soil acidity, and mobilize aluminum (Al). Much less research has focused on the associated changes in soil phosphorous (P) that should accompany alterations in secondary phases of Al and iron (Fe) in these soils. Two long-term whole watershed acidification experiments at the Bear Brook Watershed in Maine (BBWM) and the Fernow Experimental Forest in West Virginia are being studied to determine the effects of acidification on soil chemistry including fractions of P. Fractionation techniques were used to partition soil P into: labile P, Fe-P, Al-P, Ca-P, and refractory P. The Al-P fraction dominated both watersheds being 74% of the total P at BBWM and 72% of total P at Fernow. Aluminum associated P was 18% less in both the 0-10 cm and 40-50 cm depths of the acidified watershed at the Fernow Experimental Forest. Likewise, Al-P was 44% and 20% less in the 0-5 cm and 5-25 cm depths, respectively in softwood-dominated soils at BBWM. There was little difference between the reference and acidified watershed in soil P fractions at BBWM under the hardwood forest type, which may be attributable to the influence of biocycling on the liberated subsoil P.