This paper describes the preparation of an aqueous dispersion of electrostatically stabilized gold nanocrystals. It also describes the characterization of these nanocrystals by NMR, SAXS, SLS, and TEM prior to and following their modification by chemisorption of 3-mecaptopropanoic acid. Using the insights gained, these nanocrystals were subsequently modified by chemisorption and appropriate surface concentration of a disulfide biotin analogue (DSBA). Addition of streptavidin to the DSBA-modified gold dispersion results in the binding of gold nanocrystals to opposite faces of the protein and in the aggregation of the dispersion. The growth kinetics and structure of the resulting aggregates were characterized by W-visible spectroscopy, DLS, SAXS, and TEM. Some implications of these findings for the assembly of complex nanocrystal architectures in solution are considered.