While it is known that drivers as a group rate their skills as better than the average, the mechanism underlying this illusion is unclear. It is possible, for example, that it is due either to a "positive-self" or "negative-other" bias. A test of these alternative hypotheses revealed that judgments are consistent with a "positive-self" bias. An attempt was made to determine whether the illusion was present in all areas of driving skill or whether there were specific components where the illusion was absent. For men, the bias was present in all the driving components examined. For women, there were several areas where they rated themselves less positively than the men, and four areas where they showed no evidence of any bias. When the effects of driving experience were statistically controlled for, however, these sex differences were found to be substantially reduced.