The goal of knee ligament reconstruction is to return the athlete to the previous level of function as quickly and as safely as possible. The appropriate level of aggressiveness in returning the athlete to sport remains controversial. Information in the literature regarding safe return to play has been dominated by the anterior cruciate ligament (ACL) reconstruction literature. The basic concepts that hold true for returning the ACL-reconstructed athlete to play can be generalized to injuries treated nonoperatively as well. This article presents a review of the principles of rehabilitation following knee ligament reconstruction, with an emphasis on criteria for return to play.