Abstract Cognitive functions develop and change across the lifespan. Previous research has documented how normal age-related processes negatively affect cognition. Tests of memory performance, decision-making, processing speed, and executive functioning, including inhibition, set-shifting, and problem-solving ability, have been shown to steadily decline across the lifespan, with noticeable deficits clearly occurring by age 50. Although the data consistently demonstrate a decline, interindividual differences have shown great variability in the onset and extent of these changes. Additionally, investigators in the field of cognitive rehabilitation have provided support for the view that cognitive fitness can be enhanced by engaging in mentally stimulating activities and/or aerobic exercise and that such activity may delay cognitive decline and even prevent dementia.