Osteoarthritis (OA) is the most common form of arthritis and is a painful, chronically disabling joint disease that often significantly compromises function and independence. With the generalized rise in the age of the global population, the number of people suffering from musculoskeletal disorders throughout the world will increase dramatically over the coming decades. International clinical guidelines recommend exercise for the treatment of OA. Given the current and predicted future global burden of OA of the hip and knee, the aim of this chapter is to summarize the evidence from recent systematic reviews published in English on the effectiveness of land- and water-based exercise programs for people with OA of the hip and knee. The primary outcomes considered, based on the recommendations of the Outcome Measures in Rheumatology (OMERACT) conference OMERACT III, are pain and function. Recent systematic reviews have examined the effectiveness of exercise on pain and function compared with controls: landversus water-based exercise, individual versus group exercise, and exercise prior to surgery for people with OA of the hip, the knee, and lower limb (hip and knee combined). Generally, most forms of exercise have been demonstrated to have significant positive effects on pain and function at the end of the exercise program, but unless participants continue the program, the sustainability of these effects in the longer term are questionable. However, exercise appears to be a safe intervention, with few adverse effects reported. A number of considerations relating to the design and reporting of primary research in this area are discussed.