In this review article the emphasis will be on the role of the DG (dorsal and ventral) in supporting memory based on the operation of specific processes. Based on the development of computational models of dorsal dentate gyrus (dDG) and behavioral evidence based on dysfunction of dDG, this review will show that the dDG mediates mnemonic processing of spatial information. The processes subserved by dDG include (a) the operation of conjunctive encoding of multiple sensory inputs, implying an integration of sensory inputs to determine a spatial representation, and (b) pattern separation of spatial (especially metric) information, involving the reduction of interference between similar spatial locations (c) pattern separation of context (d) importance of context in object recognition, and (e) temporal integration and remote memory and spatial pattern separation based in part on neurogenesis. In addition the ventral dentate gyrus (vDG) mediates mnemonic processing of odor information as indicated by odor pattern separation.