Room-temperature adsorption of three model organosulfur compounds, dimethyl disulfide (CH3SSCH3), methanethiol (CH3SH), and dimethyl sulfide (CH3SCH3), on Si(100) has been investigated using Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), temperature-programmed desorption (TPD), and density functional theory (DFT) calculations. AES measurements show that each of these organosulfur compounds has a characteristic surface saturation coverage and reaction probability with Si(100). TPD studies indicate that methyl groups of these organosulfur compounds remain intact upon adsorption on Si(100). DFT calculations, in conjunction with our experimental results, provide insight into the most likely chemisorption channel for each organosulfur compound.