The adsorption behavior of cationic polymer particles onto wool fibers has been investigated in this study. In particular, the role of the lipid layer surrounding the wool fibers and the oxidation of wool has been studied in terms of polymer adsorption. For this, polymer particles consisting of cross-linked polystyrene cores and containing surface ammonium chloride groups have been synthesized. These colloidal particles are solely stabilized through electrostatic repulsion. It was shown that, under the same conditions, no polymer particles are adsorbed onto untreated wool while a monolayer is adsorbed onto wool of which the lipid layer has been removed. Wool oxidized with peroxomonosulfuric acid displays a very similar behavior in terms of wetting characteristics and polymer adsorption to untreated wool, despite an increased amount of cysteic acid on the fiber surface. X-ray photoelectron spectroscopy results indicate that the lipid layer is still intact after this oxidative treatment. A monolayer of polymer particles can be observed on the wool surface after the removal of the lipid layer. The enhanced adsorption of polymer particles onto untreated and oxidized wool from which the lipid layer has been removed indicates that this layer presents a major adsorption barrier for cationic polymer particles.