Anterior cruciate ligament (ACL) injuries occur mostly during sport. Approximately 70% of ACL injuries in sport occur without contact and are known as “non-contact injuries.” Over the last decade, it has been shown that many non-contact ACL injuries can be prevented through an exercise-based injury prevention program. These exercises involve balance, strengthening and practicing movements that put the ACL at less risk. In Dr. Robert Marx’s book, The ACL Solution: Prevention and Recovery for Sports’ Most Devastating Knee Injury, he reviews the principles of ACL injury prevention. This article also discusses these concepts and reviews the literature with respect to ACL injury prevention.