The adsorption of several simple methylamines on the Si(100)-(2 x 1) surface has been investigated using Auger electron spectroscopy (AES), thermal desorption spectroscopy (TDS), low-energy electron diffraction, and computational modeling. Both methylamine and dimethylamine appear to undergo mostly dissociative adsorption on this surface at room temperature, although trapping into a molecular adsorption well appears to occur to a limited extent for both molecules. Trimethylamine appears to undergo mostly molecular adsorption on this surface. These results are in agreement with recent computational, infrared, and photoemission spectroscopic studies of these systems. By comparison to the AES results from the adsorption of methyl iodide on Si(100), it was concluded that the surface saturation coverage of trimethylamine on Si(100) is 0.26 monolayers, consistent with the photoemission results, while both methylamine and dimethylamine appear to saturate at about 0.48 monolayers. TDS reveals parent desorption channels for all three of these molecules, as well as competing surface decomposition channels. The adsorption energies obtained from computational treatments of these systems are consistent with the experimentally derived values.