On tasks of explicit memory and inhibitory function, older adults have consistently been shown to perform better in the morning, while young are better in the afternoon. In the proposed set of experiments, we test the hypothesis that aging and time of day affect implicit learning of sequential regularity with elderly learning better at peak morning times. The first experiment tests both young and old on an alternating serial reaction time task (ASRT) at morning and afternoon times of day. The second experiment uses a novel variation of the ASRT to test the hypothesis that explicit sequence learning also varies with time of day. For both types of learning, time-of-day effects will be linked to frontal lobe functioning and working memory capacity as an underlying mechanism. This project has health relevance in that older people often have to learn and relearn skills that involve both implicit and explicit learning (e.g., using computers, recovering after stroke), and so it is important to determine how learning can be maximized by choosing appropriate learning [unreadable] conditions, such as time of day. This project also has implications for aging research in that age impairments seen across tasks may be exaggerated or minimized by testing at different times of day. [unreadable] [unreadable]