The incidence rate and factors that may predict a second anterior cruciate ligament (ACL) injury to the ipsilateral or contralateral knee after ACL reconstruction (ACLR) have seldom, if ever, been reported. Therefore, impairments that increase risk of future injury may persist in athletes who return to sport after ACLR. The purpose of this study was to determine the incidence of subsequent ACL injury following ACLR and identify modifiable factors predictive of a second ACL injury.