PROJECT SUMMARY/ABSTRACT This administrative supplement is proposed for parent R00 (NR016484): “A Personalized Behavioral Intervention to Improve Physical Activity, Sleep and Cognition in Sedentary Older Adults.” The parent study does not involve participants with any cognitive impairment (e.g. Alzheimer’s disease or other dementia). The purpose of this administrative supplement is to test the feasibility and preliminary effectiveness of a personalized behavioral intervention which is adapted from the parent study to promote physical activity (PA), sleep and cognitive function in older adults with mild cognitive impairment (MCI). Disturbed sleep is more frequently reported in individuals with MCI (60%) than healthy older adults and are also associated over 50% increased risk of AD, subjecting older adults with both MCI and disturbed sleep to greater risk for AD than those with MCI only and calling for the importance of sleep treatment in MCI. Emerging evidence have shown that PA interventions improve sleep and cognitive outcomes in individuals with MCI. Factors associated with aging such as decreased physical function, mobility, fear of falling, and cognitive impairment lead to low adherence of PA interventions in older adults with MCI. The emerging mHealth technology provide more innovative approaches to deliver individually tailored behavioral interventions that can accommodate a person’s health status and can become embedded in the individual’s daily routine. The interactive features (sedentary reminders, goal setting, and prompts) of these techniques has the potential to increase intervention adherence in individuals with MCI. It has not yet been widely implemented in people with MCI. We propose to conduct a pilot randomized controlled trial (RCT) in older adults with both MCI and sleep complaints to examine the feasibility of implementing mHealth technology in a 16-week behavioral intervention for older adults with MCI and the preliminary effects of the intervention on these older adults’ physical activities, sleep, and cognition, compared to a control group. To address potential memory deficits in MCI, compared the intervention in our parent study, we will use more simplified PA plans, provide more visual cues at the participant’s home, and offer additional support for PA training and mHealth technology in the intervention for MCI.This study will provide preliminary evidence for the further development, evaluation, and implementation of the intervention to support active aging and promote sleep and cognitive outcomes in individuals with MCI, which is a key theme of the National Institute of Nursing Research in its mission to enhance public health. It will inform an R01 application to determine the intervention’s efficacy on older adults with MCI’s physical activity, sleep, and cognition in a randomized controlled trial.