 A non-inferiority controlled clinical trial using randomization for allocation at the level of general practice in 21 centers in 8 Spanish regions, to compare a group Otago exercise program OEP delivered by specifically trained instructors and supplemented by prescriptive recommendations for home exercising, with an individual OEP also delivered by specifically trained professionals and supplemented by prescriptive recommendations for home exercising, with twelve months follow-up to determine the effectiveness of the OEP in terms of prevention of falls in a community-dwelling 65- to 80-year-old population. 