Evaluation of the effects of cultivation on soil properties in Ustic Mollisols has generally been limited to surface horizons. To examine the effects of cultivation on both surface and subsurface horizons, six paired virgin and cultivated pedons of Williams soil (fineloamy, mixed Typic Argiboroll) or variants of Williams from northcentral South Dakota were compared for differences in various chemical and physical properties. When similar horizons were compared, chemical differences between cultivated and virgin pedons averaged as follows: (i) organic C content was 26% less in Ap horizons; (ii) water-soluble Si was 49, 46, and 21% greater in A, Bt, and Btk horizons of cultivated pedons, respectively; (iii) water-soluble Mg, Na, and K were 42, 32, and 18% lower in C horizons of cultivated pedons, respectively; (iv) oxalate-extractable Fe was 28 and 56% higher in Ap and Bt horizons of cultivated pedons, respectively. When similar horizons were compared, physical differences between cultivated and virgin pedons averaged as follows: (i) bulk density was 18% greater in Ap horizons; (ii) Ap horizons contained 38% more very fine sand and 10% less silt; (iii) A and Btk horizons of virgin pedons possessed greater wet aggregate stability; and (iv) A horizons of virgin pedons average 30% more water retained at 0 MPa tension.