Cognitive aging is characterized by large interindividual variability at the level of behavioral performance and with respect to age-related modifications in the brain structure, function, and chemistry. The concept of reserve capacity has been proposed to account for differences between individuals in the ability to preserve a functionally and appropriate behaviour or an optimal performance. The current review aims to discuss two models of reserve capacity - cerebral and cognitive reserve - specifically in re- gards of normal and pathological cognitive aging. The value and relevance of this concept will be illustrated by taking examples from empirical studies which focus on adult age differences in cognition and their neurofunctional underpinnings. The biological and environmental determinants of the reserve capacity will be described. A particular form of reserve, that is the neural compensation, will be addressed. Finally, the extent to which the lifespan psychology integrates the concept of reserve capacity to better explain individual differences in adaptive behaviours during adult development will be underlined.