Results of surface acoustic wave, ellipsometric, and electrochemical experiments indicating that stable mono- or multilayer films result from the gas-phase chemisorption of n-alkylthiol molecules onto Au substrates are reported. Measurement of the mass and thickness of CH3(CH2)6SH films indicates a single, stable monolayer, while CH3(CH2)15SH deposition results in mono- or multilayers depending upon the experimental conditions. The first in situ kinetic measurements of the self-assembly of such layers are also discussed.