It is proposed to study the effect of inter-particle short range surface forces on the long range microstructures and structural transition in dense colloidal dispersions. Results of static and dynamic light scattering, X-ray scattering and video-microscopy will be interpreted using statistical mechanical theory and an inverse-scattering theory. Stationary and sheared dispersions will be considered in experiments. The effects of colloidal chemistry and microhydrodynamics on the structural changes and rheological properties will be analyzed. If successful, the research will have a broad range of applications related to ceramic, surfactants and polymeric suspensions.