Deposition and aggregation of small solid particles from a liquid dispersion encountered in a variety of situations in manufacturing and process technology and in natural aquatic environments. Deposition may occur onto a surfimmersed into the suspension, that is of macroscopic dimensions compared with particle, or solids may settle due to gravity to form a sediment at the bott of the vessel containing the mixture. Aggregation involves the formation assemblies of particles brought together by collisions, held in contact by surfforces. From a mechanistic point of view, deposition onto a macroscopic surf can be considered to be a limiting case of particle-particle aggregation in whone of the particles has an infinite dimension. These phenomena are of significant industrial importance in the chemienvironmental, electronics, mineral and biological sectors. For instant deposition processes are used in preparing magnetic tapes, in water purificatusing packed-bed filters, and in selective capture of solids, cells macromolecular species. Aggregation to form larger particle assemblies is also important step in enhancing the rate of gravitational settling to allow impro dewatering of suspensions, and in selective flocculation processes. It is of desirable to control the rate and extent of aggregation or deposition to control morphology of the aggregates or deposits that are being formed. Many industry operations involve both aggregation and deposition simultaneously. Particle deposition and aggregation also play an important role in the trans of pollutants in aquatic environments and in the geochemical cycling of trelements in the ocean. The transport of viruses, bacteria and particle-boureactive pollutants in soils and ground waters is controlled by the rate of part deposition. Aggregation in rivers, lakes and oceans is an important mechanism modifying the size of particles, and, subsequently, in controlling their settlrates. This book describes how such processes can be measured, modelled simulated in a systematic manner. It brings together the necessary discipline colloid and surface chemistry, hydrodynamics, experimental methods, computational methods to present a unified approach to this problem. Advaning instrumental and computational techniques are enabling the engineering these complex colloid systems to be undertaken with greater confide although many problems still need to be addressed. For example, the advantage and limitations of employing computational simulation are discussed. The thaspects of experimental measurement, modelling and simulation are intende provide an introduction to the key concepts involved augmented by bibliographic recommendations.