OBJECTIVE : To determine the validity and inter-session reliability of the Vail Sport Test™. METHODS : Cohort study-exploratory methodological research design. METHODS : Clinical Research Laboratory. METHODS : Forty-eight participants who underwent ACL-R. METHODS : Participants performance on the Vail Sport Test™ was graded by an experienced rater in real-time, and simultaneously recorded by a three-dimensional (3D) motion capture system. Construct validity was assessed using the reference standards of the camera system and the IKDC short form. To determine the between-day reliability, a subset of participants returned to repeat the test. RESULTS : There were no significant difference between the scores collected in real-time and from the kinematic data on the involved limb (p = 0.222). There was a significant difference for the uninvolved limb (p = 0.015). There was no significant difference between the scores collected in real time and those of the IKDC (p = 0.885). Good inter-session reliability (ICC = 0.787) was found for the involved limb. CONCLUSIONS : The results of this study showed good reliability and partially support the validity of the Vail Sport Test as a measure of readiness to return to play.