The authors describe a chemical patterning technique, ``microcontact insertion printing,'' that utilizes conventional microcontact printing to pattern isolated molecules diluted within a preexisting self-assembled monolayer. By modifying the preexisting monolayer quality, the stamping duration, and/or the concentration of the patterned molecule, they can influence the extent of molecular exchange and precisely control the molecular composition of patterned self-assembled monolayers. This simple methodology can be used to fabricate complex patterns via multiple stamping steps and has applications ranging from bioselective surfaces to molecular-scale electronic components.