Management of anterior cruciate ligament (ACL) injuries in adults aged >40 years has received increased attention in the literature because of an increase in the functional demands of aging athletes. Multiple structural and biomechanical age-dependent changes exist in the ACL, for example, fewer mesenchymal stem cells, decreased healing potential, decreased structural organization, decreased stiffness, and a decreased load to failure with age. As in younger patients, ACL insufficiency can predispose an older patient to the same risks of recurrent instability, meniscal and chondral injury, and osteoarthritis. The role of nonsurgical versus surgical management in these patients remains controversial. Lower-demand patients may be able to cope with ACL deficiency. Higher-demand patients may have functional instability, and the limited studies available suggest good functional outcomes with surgical reconstruction of the ACL in this population.