Statistical analyses of collected accident data have shown that incidents involving rollover represent a major safety concern based on both the frequency of occurrence and the severity level of occupant injury. Computer based models can be used to provide valuable insight into the dynamic behavior of vehicle rollover and determine the influence of basic vehicle design parameters on vehicle rollover propensity. This paper describes two computer based models which can be used to investigate vehicle rollover. The first of these models represents the Intermediate Tripped Rollover Simulation (ITRS). This computer simulation is capable of determining the response of a vehicle which slides laterally into a rigid curb, initiating vehicle rollover. The second model is the Intermediate Maneuver Induced Rollover Simulation (IMIRS) and is used to investigate untripped vehicle rollover accidents caused by sudden or excessive steering and braking inputs. Results obtained from each model are shown and general purpose sensitivity methods are applied to each model in order to investigate the relative influence of various vehicle design parameters on vehicle rollover propensity. The use of Rollover Prevention Energy Reserve (RPER) as a measure of vehicle stability is explained and demonstrated using each model.