Objectives: We sought to better understand the relationship between overtime and mental fatigue by taking into account work motivation and the quality of overtime work and studying theoretically derived subgroups. Methods: We conducted a survey-study among a representative sample of the Dutch full-time workforce (n = 1807). The prevalence of overtime work and the associations between overtime and job demands, job variety, decision latitude, fatigue, and work motivation was studied through descriptive statistics. We used MANCOVA (covariates: age, gender, salary level) to compare six overtime-fatigue subgroups with respect to work motivation and job characteristics. Results: A total of 67% of the respondents worked overtime (mean, 3.5 hours). Overtime workers appeared to be nonfatigued, motivated workers with favorable work characteristics. MANCOVA revealed no significant overtime-fatigue interaction. Conclusions: Moderate overtime is common among Dutch workers, who seem to be happy workers with attractive jobs rather than fatigued employees.