This presentation will give an overview of the use of self-assembled monolayers of alkanethiolates on gold as model substrates for studying and controlling the interactions of cells with non-natural materials. This surface chemistry approach begins with monolayers terminated in short oligomers of the ethylene glycol group, because these films are inert to the non-specific adsorption of protein. Monolayers patterned into regions presenting glycol groups with the complementary regions presenting hydrophobic surfaces are excellent substrates for patterning the attachment of cells. The immobilization of ligands to these inert films gives substrates to which proteins can selectively bind, but which otherwise rule out non-specific interactions of proteins. This approach can be extended to give substrates that mediate the attachment of mammalian cells. Monolayers presenting the peptide Arg-Gly-Asp (a ligand for cell-surface integrin receptors) mediate the selective attachment and spreading of fibroblast cells. This presentation will also discuss the design of dynamic substrates that can alter, in real time, the presentation of ligands to an attached cell and hence influence the behaviors of adherent cells. These active substrates are based on electroactive monolayers that present redox-active groups which can be switched by applying electrical potentials to the underlying gold. A first example uses substrates that can be switched to turn on the immobilization of ligands. This strategy has been used to switch regions of the substrate from an inert state to a state that permits the adhesion and migration of cells. A second example uses substrates that can selectively release immobilized ligands from the monolayer. These examples establish that self-assembled monolayers of alkanethiolates on gold are an excellent model system for controlling the adhesion of cells and will find wide use both in fundamental studies for biology and in applied targets for biotechnology.