The self-assembling adsorption/quaternization of a (dialkylamino)stilbazole nonlinear optical chromophorc precursor onto benzyl chloride-prefunctionalized surfaces is studied in situ by polarized second harmonic generation techniques. The measurements reveal that the self-assembly kinetics are approximately biexponential (I 2ω 1/2 ∼(1-α 1 e -k1t -α 2 -k2t )) with a rapid initial phase, followed by a slower second phase. The in situ measurements also indicate that the average tilt angle of the chromophore dipole moment direction with respect to the surface normal increases significantly (∼20°→42°) in the initial phases of chromophore adsorption and then remains nearly constant