In experimental time estimation research, it has consistently been found that the more a person is engaged in some kind of demanding cognitive activity within a given period of time, the more experienced duration of this time interval decreases. However, the role of individual differences has been largely ignored in this field of research. In a previous study, we tested the hypothesis that different ability groups, who are differentially demanded during cognitive task performance, differ with respect to the extent to which cognitive resources can be allocated to concurrent experience of time (Fink, A., & Neubauer, A. C. (2001). Speed of information processing, psychometric intelligence and time estimation as an index of cognitive load. "Personality and individual Differences," 30, 1009-1021.). Actually, we found brighter individuals displaying larger and more realistic subjective time estimations (STEs) than less intelligent individuals, even if both ability groups tend to underestimate actual duration length. In relating experience of time to specific mental ability constructs that are known as important sources in individual differences in psychometric intelligence, we intend to describe the STE-intelligence relationship more deeply here. In study I (n=49), we found that the STE-intelligence relationship is not exclusively restricted to speed of information processing tasks (as used in our previous study); we observed intelligence effects in timing during working memory (WM) performance as well. In study II (n=96), we assessed the relative importance of mental speed and working memory capacity in explaining the STE-intelligence relationship within one and the same experimental design. The data suggest that both mental ability constructs might be considered in explaining intelligence effects in the experience of time.