Four soils, of 15 examined, exhibited much higher adsorption of sulfate than the others.Isotopic exchange studies indicated that sulfate which is retained by soils is in kinetic equilibrium with sulfate in solution. Adsorption‐desorption studies using retentive soils also indicated that sulfate adsorption is dependent on the concentration of the equilibrium solution. The adsorption phenomena could be described by the Freundlich type equation. The data thus indicated that the sulfate‐retentive soils did not possess adsorption maxima or definite anion exchange capacities, at least up to 500 ppm. S. Although certain soils were shown to have marked capacity to retain sulfate, the sulfate could be easily desorbed. As much as 45% of the sulfate initially adsorbed could be recovered in the first water extraction.The lack of adsorption maxima is in contrast to cation‐exchange reactions where more definite exchange capacities are observed. These data suggest that either anion exchange is not involved in the retention of sulfate or that other mechanisms in addition to anion exchange are involved with sulfate retention by these soils.