The forces acting between muscovite mica surfaces across solutions containing either uncharged carbohydrates (cyclodextrin and sucrose) or a weakly charged hemicellulose (xylan) were measured using a surface force apparatus. Both the uncharged carbohydrates and xylan adsorb onto the mica basal plane. The adsorption of the uncharged carbohydrates results in a decrease in the longrange electrostatic double-layer force, thereby indicating a reduction in surface charge density. At a low ionic strength (1 x 10-3 M KBr) the adsorption of xylan is very limited, and the resulting adsorbed layer has a thickness similiar to that observed for cyclodextrin and sucrose. When the ionic strength of the solution is increased, a slow buildup of the adsorbed xylan layer takes place. The functional form of the interactions between these thicker layers is consistent with the forces expected for anchored polymer brushes in an good solvent.