Wheelchair stability is a growing concern. Between 25 and 38 percent of serious wheelchair accidents result from forward and backward tips [3, 5, 24]. A two dimensional model of a power wheelchair was developed and then validated using a series of static and dynamic tests. Certain wheelchair properties were varied to ensure that the predictions were valid for a wide range of initial conditions. The model was less stable than the actual wheelchair in both static and dynamic scenarios. The model was able to predict static tips within 4.4 degrees and dynamic tips within 3.4 degrees. The model demonstrated that the wheelchair would not tip over upon encountering curbs of up to 7.1 cm high and sudden drops of up to 20.0 cm. The utility of computer modeling as a tool in the design of safer wheelchairs was demonstrated.