Early in our longitudinal qualitative study on meaningful engagement and quality of life among assisted living (AL) residents with dementia, researchers observed differences between the activities scheduled on monthly engagement calendars and those taking place. Yet, we were unable to identify any research examining such deviations or their implications. Thus, drawing on data from three diverse AL communities studied over a one-year period, we aim to: 1) examine deviations in scheduled engagement programming; 2) identify influential factors; and 3) understand resident outcomes. Our analysis identified general adherence to calendars but also deviations involving cancellations and substitutions. Factors influencing deviations included staff and staffing, engagement capacity, programming guidance and support, care staff attitudes and beliefs, and unforeseen circumstances. Cancellations typically meant resident inactivity and sometimes boredom, disappointment, and anxiety; substitutions appear less detrimental. This analysis has implications for research and practice and underscores the significance of engagement among persons living with dementia.