The effect of handedness on cognitive functioning has been the subject of much controversy. The influential "pathological left-handedness theory" posited by Coren and Halpern (1991) claims that left-handedness is probabilistically related to deviations from the neurological and cognitive norm. Many studies have failed to find negative effects of left-handedness on cognitive functioning, but most of these studies related handedness to cognition at one moment in time. Such studies do not exclude the possibility that sinistrality may be related to a more pronounced age-related longitudinal decline in cognitive functions. This hypothesis was tested in the present study. In a longitudinal study involving a large population sample of cognitively intact people aged at least 50 years at baseline, we evaluated the effect of handedness on age-related decline in four major cognitive domains: speed of information processing, verbal learning, long-term verbal memory, and executive functioning. The results failed to provide support for the hypothesis that sinistrality is associated with a more pronounced age-related cognitive decline. Recommendations for future studies are provided.