Background/Study Context: Occupational activity is associated with cognitive functioning in older age. The mental exercise hypothesis attributes this association to differences in mental exercise at work. Methods: A case-control design was used to test the mental exercise hypothesis. Primary and secondary school teachers (aged between 25.29 and 79.01 years) and non-teacher controls were matched for level of occupation, educational level, age, and gender. Regression analyses were used to analyze the data. Possible confounders (such as precareer intelligence and depressive status) were taken into account. Results: Teachers had superior verbal fluency and working memory scanning abilities. Conclusion: The results are in line with the mental exercise hypothesis. Copyright © Taylor & Francis Group, LLC.