Background: Adult day programs provide critical supports to older adults and their family/friend caregivers. High-quality care in the community for as long as possible, and minimizing facility-based continuing care are key priorities of older adults, their caregivers, and healthcare systems. While most older adults in need of care live in the community, about 10% of newly admitted care home residents have relatively low care needs that could be met in the community with the right supports. However, research on the effects of day programs is inconsistent. The methodological quality of studies is poor, and we especially lack robust, longitudinal research. Objective: Our research objectives are to (1) compare patterns of day program use (including non-use) by province (Alberta, British Columbia, Manitoba), and time, (2) compare characteristics of older adults by day program use pattern (including nonuse), province, and time, (3) assess effects of day programs on attendees, compared to a propensity score matched cohort of older non-attendees in the community. Methods: In this population-based retrospective cohort study, we will use clinical and health administrative data of older adults (65+ years) who received publicly funded continuing care in the community in the Canadian provinces of Alberta, British Columbia, and Manitoba between January 01, 2012 and December 31, 2024. We will compare patterns of day program use between provinces and assess changes over time. We will then compare characteristics of older adults (e.g., age, sex, physical/cognitive disability, area-based deprivation indices, caregiver availability/distress) by pattern of day program use/ non-