We performed Monte Carlo simulations to study the adsorption behavior of a small flexible model surfactant on hydrophilic surfaces. A coarse-grained lattice model was used to account for excluded-volume effects and nearest-neighbor interactions. The model predicts adsorption isotherms that agree qualitatively with experimental results. The results of the simulation complete and support experimental structure investigations made with AFM, ellipsometry, and neutron reflectometry. Adsorbed bilayer structures depend on the adsorption energy. The efficiency of hydrophobization and the shielding against small polar molecules increase strongly with increasing surfactant concentration.