We report the template-directed growth of polyaniline nanostructures at Au electrodes modified with two-component self-assembled monolayers consisting of 4-aminothiophenol (4-ATP) and n-octadecanethiol (ODT). 4-ATP, which is more easily oxidized to the cation radical than aniline, serves as a nucleation site for the electrochemical deposition of polyaniline. Therefore, when 4-ATP/ODT mixed monolayers are oxidized in the presence of aniline, polyaniline features are formed selectively from islands of 4-ATP embedded in the ODT monolayer. The size and distribution of these features were characterized by AFM. In this work, we show that the feature density is a function of monolayer composition and that the feature height is dependent on the concentration of aniline in solution.