By use of an ultrathin film of microphase-separated poly(styrene-block-methyl methacrylate) as a template, nanometer-scale patterns of tetraalkylammonium passivated palladium colloids can be generated. This pattern serves, in turn, as the template for the electroless deposition of semicontinuous 20 nm wide copper nanostructures, which is approximately a factor of 2 smaller than feature sizes that can be generated by state-of-the-art lithographic processes.