Direct caregivers in nursing homes are the certified nursing assistants (CNAs) who provide the majority of hands-on care. This study administered a knowledge instrument to a sample of CNAs () employed at nursing homes in a northeastern city to evaluate their knowledge in the domains of aging, cognition, and mental health. This study found that despite working with older adults on a daily basis, the CNAs had less than average knowledge in these areas. They demonstrated deficits in knowledge in all three domains. Implications for CNA education and regulation are discussed.