It has been known for some time that many individuals will exhibit deficits in memory that are unrelated to neuropathologies. This subtle age-associated decline in normal memory function is not as drastic as the devastating effects of Alzheimer disease, but is nevertheless unsettling. Biological studies of the human nervous system are difficult for many reasons, including ethical issues of invasive studies in living persons and the nearly impossible task of controlling for all genetic and environmental variables among individuals. To investigate normal age-related impairments at the neuronal or synaptic level with the greatest range of experimental techniques, animal models must be used. However, animal studies have the limitation that animals cannot describe their experiences directly, making the investigation of certain cognitive functions, such as episodic memory, difficult. To make inferences about the aging process from the animal model back to the human, rigorous behavioral paradigms must be used to ensure that the same function is being examined across species. Fortunately, the domain of spatial memory provides a common ground between species and happens to be a domain where age-related deficits are described consistently for humans, nonhuman primates, and species such as dogs, rats, and mice. Because of its critical role in memory in general, and specifically in spatial memory, the hippocampus has been the focus of a productive line of research into the mechanisms of normative aging.