A combination of fluorescence spectroscopy and dynamic laser light scattering is used to investigate the relationship between the extent of hybridization on the surface of DNA-functionalized gold nanoparticles and the hydrodynamic radius (R-h) of the nanoparticle. The hydrodynamic radius of the DNA-Au conjugate increases measurably only after similar to 5-10 DNA hybridization events and saturates at its maximum value well before the surface is fully loaded.