A two-degree-of-freedom Roll Simulator has been developed to study the occupant kinematics of Recreational Off-Highway Vehicles (ROVs). To validate the roll simulator, test data was collected on a population of ROVs on the market today. J-turn maneuvers were performed to find the minimum energy limits required to tip up the vehicles. Two sets of tests were performed: for the first set, 10 vehicles were tested, where the motion was limited by safety outriggers to 10-15 degrees of roll; and for the second set, three of these vehicles were re-tested with outriggers removed and the vehicle motion allowed to reach 90 degrees of roll. These quarter-turn rollover tests were performed autonomously using an Automatic Steering Controller (ASC) and a Brake and Throttle Robot (BTR).Lateral and longitudinal accelerations as well as roll rate and roll angle were recorded for all tests. The mean peak lateral and longitudinal accelerations for the initial tests were found to be 0.67 g and 0.19 g, respectively. For the autonomous tests, the peak roll rates were found to be in the range of 170-175 deg/sec. This data was used as a basis for input conditions used for the roll simulator. Comparisons between in-field test data and the roll simulator illustrated that the roll simulator has the capability of attaining the acceleration levels established with the outrigger-limited in-field tests. Further comparisons showed that the roll simulator can also follow the acceleration and roll motion trends from the autonomous tests as well as meet the peak roll rate.