Interactions between applied liming material (Ca(OH)2 or CaSiO3) and phosphate, and their order of addition, on the levels and forms of extractable Al and phosphate in a Spodosol (pH 4.2) under laboratory conditions were studied. Concentrations of extractable Al were lower when phosphate, rather than liming, materials were added first. Addition of Ca(OH)2 resulting in soil pH (water) values of 5.6 and 6.1 clearly decreased concentrations of oxalate-extractable Al. Although the addition of CaSiO3, at the same equivalent rate of Ca, resulted in similar soil pH (water) values to Ca(OH)2 treatments, concentrations of oxalate-extractable Al were virtually unchanged following CaSiO3 additions. Additions of both liming materials decreased concentrations of soluble and exchangeable Al, but such decreases were very much more marked in the case of Ca(OH)2 than CaSiO3. Stable amorphous hydroxy-Al-silicate products were formed in the CaSiO3-treated soil while semicrystalline or crystalline Al hydroxides predominated in the Ca(OH)2-treated soil. The effect of form of liming material on phosphate availability depended upon which extractant was used; nevetheless, phosphate extractability was greater when liming material rather than phosphate was added first. Increasing additions of Ca(OH)2 decreased NaHCO3-extractable phosphate, but the decrease was much less pronounced when CaSiO3 was used. In contrast, the decrease in resin-extractable phosphate with increasing rates of liming materials was much greater for CaSiO3 than Ca(OH)2 treatments. Bray-1 phosphate was unaffected by Ca(OH)2 or CaSiO3 treatment when phosphate was added first, though if either liming material was added first, phosphate extractability was increased, irrespective of the rate or form of liming material.