The purpose of the study was to determine the effects that achievement and locus of control have on a person's ability to estimate the passage of time. The subjects were a group of 116 college students enrolled in an introductory psychology course at Mountain View College. Achievement was measured by the grade obtained in the course, and the locus of control was measured by the individual's score obtained on the Rotter Internal-External Locus of Control Scale. Five different cutoffs were used to determine the locus of control orientation (internal/external). The data were analyzed using analysis of variance techniques. No significant differences between any of the groups were found.