This chapter aims to examine the evidence that physical activity can attenuate age-related bone loss. It describes the nature of age-related changes to the skeleton, the typical response of normal bone tissue to controlled mechanical loading, and the effect of exercise intervention on the skeleton during aging. It also considers the modulating influence of factors such as muscle strength, calcium supplementation, and hormone replacement therapy on that effect. Important factors contributing to bone loss during adult life include bone remodeling inefficiency, sedentary life-style with associated reduced habitual bone loading, inadequate nutrient intake and assimilation (particularly calcium), reduced muscle strength, and age-related attenuation of the adaptive capacity of bone. Exercise intervention targets reduced skeletal loading and muscle weakness. The weight of evidence supports a conclusion that exercise is an effective strategy for the maintenance of skeletal health. Intervention trials in humans suggest that certain forms of exercise may, at a minimum, halt or slow age-related bone loss and, in some instances, actually improve bone mass in a site-specific manner.