Development of memory depends upon changes in several mnemonic processes, which are illustrated in experiments with normal and mentally retarded adults and children. The principal focus is upon spontaneous learning strategies, including active rehearsal and specialized non-rehearsal, both of which are found to change systematically with age. In addition, there are developments in the relation of learning strategy to changing recall task demands. Finally, it appears that retrieval of rehearsed material is more rapid in older and more intelligent people, but this is nottrue for retrieval of non-rehearsed material.