Rupture of the anterior cruciate ligament (ACL) in footballers has deleterious consequences on several levels. It involves long periods "off the field" with considerable socio-economic impacts in terms of primary costs (care, time off work) and secondary costs (care and long-term disability from gonarthrosis). Prevention programs have been introduced and proven to be effective in reducing the rate of ACL injuries. In our book, we will try to elucidate the different ways of preventing ACL rupture, both primary and secondary.