This paper presents the results of an in-depth study of the measurement of occupant kinematic response on the S-E-A Roll Simulator. This roll simulator was built to provide an accurate and repeatable test procedure for the evaluation of occupant protection and restraint systems during roll events within a variety of occupant compartments. In the present work this roll simulator was utilized for minimum-energy, or threshold type, rollover events of recreational off-highway vehicles (ROVs). Input profiles for these tests were obtained through a separate study involving autonomous full vehicle tests . During simulated roll events anthropomorphic test device (ATD) responses were measured using on-board high speed video, an optical three-dimensional motion capture system (OCMS) and an array of string potentiometers. Comparisons among the indirect measurement systems were performed to allow for characterization of each measurement system's utility and accuracy when used in this specific application. These comparisons show that the indirect methods detailed in this study allow for accurate and repeatable ATD excursion measurement. Preliminary evaluations were also made between the roll simulator ATD response and that determined during the autonomous tests. The roll simulator ATD kinematics closely matched those observed and recorded during autonomous tests. These comparisons provide an initial verification of the roll simulator system with respect to reproducing ATD kinematics and a validation of the measurement system methodologies employed on the roll simulator.