Self-assembled monolayers of a small bifunctional molecule (4-carboxythiophenol) have been formed on Al and Au surfaces. The nature of coordination of the molecules to the two metal surfaces is different, leading to different terminal functionality of the monolayer surface. This aspect has been favorably exploited to self-assemble Ag particles from a colloidal solution on the monolayer-covered Al surface which is thiol rich. The self-assembly of the Ag particles does not take place on the monolayer-covered Au surface with carboxylic acid surface functionality. The adsorption of the monolayer on Al and Au surfaces and Ag colloidal particles on the self-assembled monolayer has been followed using electron microscopy, quartz crystal microbalance, and X-ray photoemission measurements. The two-dimensional array of strongly bonded metal nanoparticles shows potential for application as metal-supported catalysts and sensors, generation of submicrometer electronic devices, high density data storage, etc.