An atomic force microscope was used to measure forces between self-assembled monolayers (SAMs) of hexadecanethiol as a function of solvent type, Solvents alter interactions between surfaces by changing the wetting properties of the surface. Adhesive forces decrease with solvent dielectric constant and vary monotonically for mixtures of water and ethanol, ethanol and methanol, and water and ethylene glycol, This study demonstrates that interactions and adhesion between hydrophobic SAMs can be manipulated through changes in the contact angle of the surface.