The colloidal probe technique was used to accurately measure forces between water–solid interfaces of negatively charged latex particles in aqueous solutions of linear, cationic oligoamines of different valence up to roughly +4. These measurements were realized between pairs of particles with the atomic force microscope. Monovalent and divalent amines behave as simple electrolytes, and the forces are dominated by double layer repulsion at low concentrations and van der Waals attraction at high concentrations, as suggested by the classical theory by Derjaguin, Landau, Verwey, and Overbeek (DLVO). Additional attractive non-DLVO force of a short range can be evidenced, and its origin is attributed to hydrophobic interaction between the surfaces. Trivalent and tetravalent oligoamines induce a charge reversal and equally an additional attractive non-DLVO force. The charge reversal originates from the adsorption of these oligoamines to the particle surface. The additional non-DLVO force is more long-ranged than the ones observed in the presence of amines of low valence. This additional attraction is probably related to ion–ion correlations, existing surface heterogeneities, and the chainlike nature of the amines investigated.