Although carbodiimides and succinimides are broadly employed for the formation of amide bonds (i.e., in amino acid coupling), their use in the coupling of peptides to water-soluble carboxylic-terminated colloidal gold nanoparticles remains challenging. In this article, we present an optimization study for the successful coupling of the KPQPRPLS peptide to spherical and rodlike colloidal gold nanoparticles. We show that the concentration, reaction time, and chemical environment are all critical to achieving the formation of robust, peptide-coated colloidal nanoparticles. Agarose gel electrophoresis was used for the characterization of conjugates.