Polymer impacts on soil physical properties are thought to be a function of its adsorption and desorption by the soil material. This chapter reviews published results of polymer sorption studies with emphasis on synthetic polymer application to soil rather than biologically synthesized polymer in situ. The following statements summarize the main findings of polymer adsorption studies. Adsorption of polymers on pure clays is strongly influenced by electrostatic attraction whereby the order of adsorption of polymers is cationic > nonionic > anionic. Polymer adsorption occurs on the external surface of clay packages. Therefore, the effects of factors such as clay type and electrolyte composition on adsorption are manifested by their effects on microstructure of clay packages. High molecular weight polymers do not penetrate soil aggregates so that adsorption on soil materials is related to soil aggregate size and molecular conformation of the polymer rather than total soil surface area and electrostatic charge interactions. Very little polymer desorption occurs when the system is kept wet, and most of the polymer in solution becomes irreversibly bonded to the soil by drying the soil