Organic monolayers may be grafted onto silicon surfaces using an in situ electrochemical patterning method. In this technique, dielectric templates such as polystyrene spheres (epsilon = 2.5) or poly(dimethylsiloxane) stamps (epsilon = 2.3-2.8) are placed in close proximity to, or in direct contact with, silicon electrodes while a potential is applied to drive electrografting reactions. In this work, the authors describe methyl monolayer patterns created in anodic processes and phenylacetylene monolayer patterns created in cathodic processes. Both anodic and cathodic processes show similar chronoamperometric behavior, suggesting silicon passivation associated with the formation of monolayers. Atomic force microscopy shows the sizes, geometries, and thickness of patterned films. Comparison of experimental results with electric field simulations also shows that solution resistance controls the feature sizes, resulting from electrografting with proximal dielectric templates. Similarly, electrochemical impedance spectroscopy shows that the films are densely packed with relatively low levels of defects. The versatile technique is further demonstrated as a monolayer resist for patterned electrodeposition of copper on silicon. (C) 2010 The Electrochemical Society. [DOI:10.1149/1.3463712] All rights reserved.