Electrostatically stabilized aqueous dispersions of nanometric-sized silica particles have been characterized by light scattering, small angle X-ray scattering, and osmotic pressure measurements. All three studies yield similar values for the particle size, molecular weight, and particle surface charge. In addition, good agreement is found between directly measured osmotic pressure values and those calculated from scattering studies. Using the particle properties as determined from the three experiments, the osmotic pressure as a function of volume fraction is compared to liquid state theory models with no adjustable parameters. Finally, small angle X-ray scattering studies indicating the presence of long-range order in moderately to highly concentrated dispersions are reported.