Mobility can be defined as the ability to move or be moved freely and easily. In older adults, mobility impairments are common and associated with risk for additional loss of function. Mobility loss is particularly common in these individuals during acute illness and hospitalization, and it is associated with poor outcomes, including loss of muscle mass and strength, long hospital stays, falls, declines in activities of daily living, decline in community mobility and social participation, and nursing home placement. Thus, mobility loss can have a large effect on an older adult's health, independence, and quality of life. Nevertheless, despite its importance, loss of mobility is not a widely recognized outcome of hospital care, and few hospitals routinely assess mobility and intervene to improve mobility during hospital stays. The Quality and Performance Measurement Committee of the American Geriatrics Society has developed a white paper supporting greater focus on mobility as an outcome for hospitalized older adults. The executive summary presented here focuses on assessing and preventing mobility loss in older adults in the hospital and summarizes the recommendations from that white paper. The full version of the white paper is available as Text S1. J Am Geriatr Soc 67:11–16, 2019.