The Preferences Scale of morningness was originally conceived as a two-factor, 11-item model. More recently, a two-factor, six-item model has been developed and supported in two independent samples. These competing models were examined using structural equation modeling in a mixed student and working sample (n = 120). The results supported the two factor, six-item model (x2(8, N = 120) = 10.84, p > 0.05) as best fitting the sample data. The two factors explained 59% of the variance and Cronbach’s alpha was 0.71. Significant differences ( p < 0.01) in self-reported driving ability between morning and evening types were obtained by time-of-day, providing some evidence of construct validity. Morning types rated their performance as better in the morning hours and evening types rated their performance as better at night. We then examined whether self-rated performance is subject to some degree of bias. For both morning and evening types, there was a tendency for those scoring high on self-deception to rate their driving ability as better, but these differences were not significant.Overall, these findings suggest that self-ratings are suitable for use in determining construct validity. Recommendations for future studies are made.